RobertHorry
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As part of my break from work, I will delve into the 3-4 defense and the technicalities of it. I will void the D-Line explanation as it seems we are more than set at the front 3. Its a pretty long read. For those who do not know, the Miami Dolphins run a 3-4 defense.
ILB/OLB:
The inside linebackers must be stout in run support. Because there are only 3 DL to match up against 5 OL, they must be able to stack and shed an unblocked offensive lineman in the running game. The left inside linebacker is called the “MIKE" linebacker (keep in mind that different teams might use different nomenclature for the different positions). He closely resembles his counterpart in the 4-3 except that he aligns himself in a “2" technique over the guard to the tight end side. The right inside linebacker, referred to as the “MAC" Linebacker also aligns himself in a “2" technique except he is on the “weak side” away from the tight end. In the 3-4’s most basic form both the “MIKE” and “MAC” linebackers have “A" and "B" gap responsibility, so like the middle linebacker of the 4-3 they must play the run from the inside out. However, in many of the 3-4 scheme’s seen today you see the “MAC" backer playing more of a weak side linebackers role and the “MIKE” can likewise find himself in the strong side role. The strong-side "MIKE", must have an attacking style of play to come up and meet a ball carrier at the line of scrimmage and be fast enough to string him out to the sideline. Though his first priority would be to stand the blocking back up in the hole yet plugging another running lane.The weak-side "MAC", is responsible for backside pursuit and must be disciplined enough not to overrun a play which could result in a big gain. Both players also must be able to blitz the QB and be able to drop into short zone depending on the defense called. Personnel wise the inside linebackers in the 3-4 are usually the prototypical linebacker that runs a 4.5 to 4.7 in the forty and stands 6’ to 6’4”tall at 240-255lbs. Most linebackers that play inside in a 3-4 scheme can usually translate well to the middle and weak side linebacking positions in a 4-3.
A telling quote of what the ILB (Crowder/Ayodele) need to do is explained in Ray Lewis's quote.
"We're in the 46 defense now, and finally, finally again, I get to play football," said Lewis. "My job is not to take on offensive linemen like it was in the 3-4, but now to make running backs not want to play against me"
The two outside linebackers of the 3-4 defense have very similar jobs, especially in the very basic concept of the defense. An OLB in this defense is simply stated, the pass rusher. Both the “SAM” (strong-side) and “WILL” (weak-side) of the 3-4 will usually have “D gap” responsibility and will line up outside of the DE as a 5/7 technique (outside shoulder of either OT or TE). He is the guy who chases down the QB. His ideal frame is tall in the 6'4" range and normally anwhere from 240-260 lbs. Long arms are needed to disengage from NFL offensive tackles in the run game and also used in pass rush. They must be very fast as to be able to beat a Tackle to the corner in pass rush but also strong and athletic enough to utilize bull rush moves when needed. This player is also responsible for outside contain in the run game.
When Coach Hank Stram first introduced the 3-4 to the NFL it was four legitimate linebackers playing zone defense behind three down linemen. Later on teams started replacing one of those outside linebackers with a pure pass rusher and now the most prevalent version has both outside linebackers rushing the passer from a defense that more closely resembles a 5-2. On almost every play, 1 of the OLBs will rush the QB. The OLBs can play from a 2 or 3-point stance.
There is part why we failed so much at defense last year. Jason Taylor and Joey Porter were unable to generate much pressure when going 1 on 1.
CB
A cornerback (CB) in this defense has many different responsibilities from a traditional zone coverage CB. This player needs to be very fast with good ball skills as he plays alot of man coverage due to the schemes employed, dependant on what the front 7 does. Certain packages will also ask this player to play a variety of zones. The CB also be must tough enough to help support the outside run game. Normally, due to defensive formations, these players will line up on the WR with a 5 to 7 yard cushion as to not get beat at the line scrimmage and surrender a deep pass play due to the extra safety playing in the box on run support, better known as cover 3. The roles of a CB vary greatly depending the defensive playcall and responsibility of the safety.
S
Like a Safety (S) in any defense, they must be able to play centerfield to be successful. Due to the versatility of the defense, its common to only have one deep safety in the pass game, which is why referring back the CB's will line up with a cushion b/c there isnt alot of help there. These players make all the secondary calls and must be strong in second level run support. The free safety (FS) is responsible for reading the offensive plays and covering deep passes. Depending on the defensive call, he may also provide run support. He is positioned 10 to 15 yards behind the line of scrimmage, toward the center of the field. He provides the last line of defense against running backs and receivers who get past the linebackers and cornerbacks. He must be a quick and smart player, capable of making tackles efficiently as well as reading the play and alerting his team of game situations.
The strong safety (SS) is usually larger than the free safety and is positioned relatively close to the line of scrimmage. He is often an integral part of the run defense, but is also responsible for defending against a pass; especially against passes to the tight-ends.
SCHEMES
Without a doubt the 3-4 defense is the poster boy for flexibility. The strength of this defense rests in the number of quick footed athletes you can place on the field at the same time. It is so versatile of a defense that you could be in what appears to be a 5-2 defense on one play and then drop back in to a 4-2-5 zone on the next. Zone blitzing is especially effective from the 3-4 because you have so many players who can do similar things. You almost have endless combinations of the zone blitzes you can call. This is what has made Bill Belichick and Romeo Crennel so successful over the past; they were completely unpredictable and nobody had any idea what they are going to do next. They did so many different things every week that at times it seemed like they were drawing defensive calls out of a hat.
On the defensive line, the two most commonly used schemes are the "2" and "1" gap. In the "2" gap, the defensive lineman are responsible for the gap to either side of their technique. For instance, the NG, in a "0" technique (head up on the center) would have the job of covering either gap between the OC and the OG's. He accomplishes this by driving into the OC and then shedding him once he reads which gap the play will come to. At the very least, he hopes to tie up the OC and at least one of the OG's and keep them off the inside linebackers. Same applies for the DT's. This is why in a typical 3-4 defense, the ILB's will have the majority of the tackles. The "2" gap is usually know as the Fairbanks-Bullough, named after Chuck Fairbanks and Hank Bullough, two early innovators of the 3-4 as mentioned previously.
In the "1" gap, the defensive lineman will have a single gap responsibility. This system is not what people think of when they think of the 3-4, because the original 3-4 was/is strictly a 2-gap system. The Phillips is named after "Bum Phillips". Bum learned under Paul "Bear" Bryant at A&M and had coached high school football well enough to break into the college ranks (not a common route). He was a defensive coordinator in SD, then in HOU (that's the Oilers for you young folks). He later was a head coach in HOU and later for NO.
Phillips was an innovator who turned the 3-4 upside down. His system is one-gap. The DL penetrates, and is charged with constant harrasment of the QB. The LBs are typically fast, and at least one of them will blitz on any given play.
The reason for the near constant 1-LB blitz is to account for the fact that the outnumbered DL is also relatively undersized and only one-gapping. However, the adjustments work out well. The OL never knows who the blitzer will be, or where he will come from. The Phillips is more aggressive that the Bullough. The school of thought for the Phillips 3-4 is the need to pressure against the QB to stop the pass threat, and this is done by varying who the "fourth rusher" (who is really a blitzer) is. Add another blitzer in here and there, and the speedy/aggressive Phillips system is a threat to QBs, and attempts to get turnovers by slashing the time that a QB has to make decisions.
Another system is the Lebeau Zone Blitz and the theme for the Lebeau system is attack, attack, attack. The Zone Blitz is very nasty thing to deal with. In terms of player types, one can vary the NT type and even the DEs, but 1 gap speed DEs are much more common.
The zone blitz play (also know as a zone fire play) has been around for ages. Dick Lebeau took the play and turned it into a full system for Pittsburgh in the early 90's. He tried his hand at head coaching and being a coordinator elsewhere, but with little success. He doesn't seem to be a good manager, and isn't great at adopting to the existing systems of other teams. What Lebeau is know for it two things. His players love him (they play hard for him), and he is an excellent theoretician who develops elaborate plays with many twists.
The idea is that the different DLs will often drop back into coverage, while several linebackers (and even defensive backs) will blitz. The OL can't brace themselves, because if they do they will likely brace for the wrong assault. This is the one defense that prides itsself on turning the tables - the defensive line and the LBs hit the OL hard and often and try to wear down the other side.
CBs most often jam or jack the WRs , then either drop into zone or blitz. SAFs either zone or blitz (a safety blitz is called a "monster"), the LBs blitz most often, and sometimes zone, the DL either rushes or ends up in zone. It's a very fun defense to watch.
This defense tries to stop the run by penetrating the OL and disrupting the offense's backfield. They stop the pass by targetting the QB with heavy blitz packages. The zone blitz is very effective against screen passes, wreaks havoc against check offs by QBs (because the zones can't be anticipated, nor can the rush), and is the only major defensive scheme that is predicated on wearing down the OL instead of the OL wearing down the DL. For these reasons, the timing system used by many spread offenses can face more troubles here than in many other systems.
There is one glaring weakness. You drop a DL into a zone and the blitz doesn't hurry the QB and the QB has a quick-realease for an arm... well your defensive lineman isn't probably going to match a WR or TE going for a reception, is he?
Another scheme that makes the 3-4 so flexible is the Over/Under. In this alignment, the linebackers rotate can "rotate" or "slide" to the "Over" (towards the strong side) or the "Under" (towards the weak side). The rotating OLB moves up to the line of scrimmage and plays the "50" or "60" technique (adding the "0" means he is lined up off the line of scrimmage on the OT or TE outside shoulder). He can be in either a three-point or two-point stance. The two ILB's rotate to a "40" and "10" technique and the backside OLB now plays the "40" technique. While this alignment can easily be confused with a 4-3, it is definitely different. Either OLB can be in blitz, stunt or coverage. By moving the OLB to a "60" technique (slightly outside of the TE) it puts him in great position to either jam the TE, a speed rush, or coverage in the shallow flats. Also, the backside OLB can loop around the tackle for an outside rush or overload the weak side protection by blitzing the "A", "B", or "C" gap. The Over/Under also yields itself well to the zone blitz and makes it very easy to disguise coverages.
PASS COVERAGE
Coverages as defined by Wikipedia are:
* Cover Zero - Strict man-to-man coverage with no help from safeties (usually a blitz play with at least five men crossing the line of scrimmage)
* Cover One - Man-to-man coverage with at least one safety not assigned a player to cover who can help out on deep pass routes.
* Cover Two - Zone coverage with the safeties playing deep and covering half the field each.
* Cover Three - Zone coverage as above, but with extra help from a cornerback, so that each player covers one-third of a deep zone.
* Cover Four - As above, with the corners and safeties dropping into deep coverage, with each taking one-fourth of the width of the field. Also referred to as Quarters.
The effectiveness of a defense against short passes and the run generally drops as it goes from Cover Zero to Cover Four, while their effectiveness against deep passes increases.
These are basic secondary coverages that can be utilized by just about any defensive formation.
What makes the 3-4 defense so unique is that if the proper players man the defense, the extra LB allows more versatility in coverage. An extra athletic player in the lineup can be used to confuse QB's of where his coverage responsibilities will lie. For instance, in a 4-3 defense zone, its pretty common for the MLB to man the zone in the middle of the field. But in a 3-4 defense, either one of the ILB's could play middle zone, or for instance, a blitz could come off the edge and the extra LB could run to cover the blitzers area after the snap.
Its also common for this defense to utilize bracket coverage. Bracket coverages are prevalent in this defense due to an extra athlete on the field. Eight (4 LB's/4 secondary) versus losing the extra LB in a 4 man front. There are two types:
1. short/deep...also known as over/under where one player will attempt to take away any underneath patterns without fear of getting beat deep because he will have help. EX. When you see a LB lined up on a WR, he isnt playing him man to man, he's merely attempting to take away slant and curl patterns with help over top
2. inside/out...this coverage is when one player attempts to take away out patterns and sideline patterns while another player attempts to take away underneath inside patterns. EX. A CB on a slot WR will line up with outsided technique (outside shoulder of WR) only allowing him to release inside where a LB is waiting to take away slant patterns.
In addition, a popular coverage is the man-under zone. In this coverage scheme, you could have any combination of man to man match ups along with other players covering zones in the field. For instance, you could have your CB's locked-up in man coverage with safeties playing a two deep zone. This type of coverage allows defensive backs to play tight at the line of scrimmage to disrupt the receivers pattern. It also great for stopping the quick-out patterns and quick screens. The downside to this coverage is that you could have a LB covering a RB or TE in space. This is generally a mismatch.
The 3-4 lends itself into easily adapting to nickel or dime coverages. Replace a LB with a DB and you have a nickel. Replace another and you have a dime defense.
The 3-4 Defense is a great defense to run if you have a coordinator that understands how to bring pressure from all different angles. A prime example is the New Orleans game. This is the only game in which the 3-4 was run with success. Albeit only for the first half, but it demonstrated what the 3-4 defense can do to QBs. Drew Brees was flustered and we went up 24-3.
ILB/OLB:
The inside linebackers must be stout in run support. Because there are only 3 DL to match up against 5 OL, they must be able to stack and shed an unblocked offensive lineman in the running game. The left inside linebacker is called the “MIKE" linebacker (keep in mind that different teams might use different nomenclature for the different positions). He closely resembles his counterpart in the 4-3 except that he aligns himself in a “2" technique over the guard to the tight end side. The right inside linebacker, referred to as the “MAC" Linebacker also aligns himself in a “2" technique except he is on the “weak side” away from the tight end. In the 3-4’s most basic form both the “MIKE” and “MAC” linebackers have “A" and "B" gap responsibility, so like the middle linebacker of the 4-3 they must play the run from the inside out. However, in many of the 3-4 scheme’s seen today you see the “MAC" backer playing more of a weak side linebackers role and the “MIKE” can likewise find himself in the strong side role. The strong-side "MIKE", must have an attacking style of play to come up and meet a ball carrier at the line of scrimmage and be fast enough to string him out to the sideline. Though his first priority would be to stand the blocking back up in the hole yet plugging another running lane.The weak-side "MAC", is responsible for backside pursuit and must be disciplined enough not to overrun a play which could result in a big gain. Both players also must be able to blitz the QB and be able to drop into short zone depending on the defense called. Personnel wise the inside linebackers in the 3-4 are usually the prototypical linebacker that runs a 4.5 to 4.7 in the forty and stands 6’ to 6’4”tall at 240-255lbs. Most linebackers that play inside in a 3-4 scheme can usually translate well to the middle and weak side linebacking positions in a 4-3.
A telling quote of what the ILB (Crowder/Ayodele) need to do is explained in Ray Lewis's quote.
"We're in the 46 defense now, and finally, finally again, I get to play football," said Lewis. "My job is not to take on offensive linemen like it was in the 3-4, but now to make running backs not want to play against me"
The two outside linebackers of the 3-4 defense have very similar jobs, especially in the very basic concept of the defense. An OLB in this defense is simply stated, the pass rusher. Both the “SAM” (strong-side) and “WILL” (weak-side) of the 3-4 will usually have “D gap” responsibility and will line up outside of the DE as a 5/7 technique (outside shoulder of either OT or TE). He is the guy who chases down the QB. His ideal frame is tall in the 6'4" range and normally anwhere from 240-260 lbs. Long arms are needed to disengage from NFL offensive tackles in the run game and also used in pass rush. They must be very fast as to be able to beat a Tackle to the corner in pass rush but also strong and athletic enough to utilize bull rush moves when needed. This player is also responsible for outside contain in the run game.
When Coach Hank Stram first introduced the 3-4 to the NFL it was four legitimate linebackers playing zone defense behind three down linemen. Later on teams started replacing one of those outside linebackers with a pure pass rusher and now the most prevalent version has both outside linebackers rushing the passer from a defense that more closely resembles a 5-2. On almost every play, 1 of the OLBs will rush the QB. The OLBs can play from a 2 or 3-point stance.
There is part why we failed so much at defense last year. Jason Taylor and Joey Porter were unable to generate much pressure when going 1 on 1.
CB
A cornerback (CB) in this defense has many different responsibilities from a traditional zone coverage CB. This player needs to be very fast with good ball skills as he plays alot of man coverage due to the schemes employed, dependant on what the front 7 does. Certain packages will also ask this player to play a variety of zones. The CB also be must tough enough to help support the outside run game. Normally, due to defensive formations, these players will line up on the WR with a 5 to 7 yard cushion as to not get beat at the line scrimmage and surrender a deep pass play due to the extra safety playing in the box on run support, better known as cover 3. The roles of a CB vary greatly depending the defensive playcall and responsibility of the safety.
S
Like a Safety (S) in any defense, they must be able to play centerfield to be successful. Due to the versatility of the defense, its common to only have one deep safety in the pass game, which is why referring back the CB's will line up with a cushion b/c there isnt alot of help there. These players make all the secondary calls and must be strong in second level run support. The free safety (FS) is responsible for reading the offensive plays and covering deep passes. Depending on the defensive call, he may also provide run support. He is positioned 10 to 15 yards behind the line of scrimmage, toward the center of the field. He provides the last line of defense against running backs and receivers who get past the linebackers and cornerbacks. He must be a quick and smart player, capable of making tackles efficiently as well as reading the play and alerting his team of game situations.
The strong safety (SS) is usually larger than the free safety and is positioned relatively close to the line of scrimmage. He is often an integral part of the run defense, but is also responsible for defending against a pass; especially against passes to the tight-ends.
SCHEMES
Without a doubt the 3-4 defense is the poster boy for flexibility. The strength of this defense rests in the number of quick footed athletes you can place on the field at the same time. It is so versatile of a defense that you could be in what appears to be a 5-2 defense on one play and then drop back in to a 4-2-5 zone on the next. Zone blitzing is especially effective from the 3-4 because you have so many players who can do similar things. You almost have endless combinations of the zone blitzes you can call. This is what has made Bill Belichick and Romeo Crennel so successful over the past; they were completely unpredictable and nobody had any idea what they are going to do next. They did so many different things every week that at times it seemed like they were drawing defensive calls out of a hat.
On the defensive line, the two most commonly used schemes are the "2" and "1" gap. In the "2" gap, the defensive lineman are responsible for the gap to either side of their technique. For instance, the NG, in a "0" technique (head up on the center) would have the job of covering either gap between the OC and the OG's. He accomplishes this by driving into the OC and then shedding him once he reads which gap the play will come to. At the very least, he hopes to tie up the OC and at least one of the OG's and keep them off the inside linebackers. Same applies for the DT's. This is why in a typical 3-4 defense, the ILB's will have the majority of the tackles. The "2" gap is usually know as the Fairbanks-Bullough, named after Chuck Fairbanks and Hank Bullough, two early innovators of the 3-4 as mentioned previously.
In the "1" gap, the defensive lineman will have a single gap responsibility. This system is not what people think of when they think of the 3-4, because the original 3-4 was/is strictly a 2-gap system. The Phillips is named after "Bum Phillips". Bum learned under Paul "Bear" Bryant at A&M and had coached high school football well enough to break into the college ranks (not a common route). He was a defensive coordinator in SD, then in HOU (that's the Oilers for you young folks). He later was a head coach in HOU and later for NO.
Phillips was an innovator who turned the 3-4 upside down. His system is one-gap. The DL penetrates, and is charged with constant harrasment of the QB. The LBs are typically fast, and at least one of them will blitz on any given play.
The reason for the near constant 1-LB blitz is to account for the fact that the outnumbered DL is also relatively undersized and only one-gapping. However, the adjustments work out well. The OL never knows who the blitzer will be, or where he will come from. The Phillips is more aggressive that the Bullough. The school of thought for the Phillips 3-4 is the need to pressure against the QB to stop the pass threat, and this is done by varying who the "fourth rusher" (who is really a blitzer) is. Add another blitzer in here and there, and the speedy/aggressive Phillips system is a threat to QBs, and attempts to get turnovers by slashing the time that a QB has to make decisions.
Another system is the Lebeau Zone Blitz and the theme for the Lebeau system is attack, attack, attack. The Zone Blitz is very nasty thing to deal with. In terms of player types, one can vary the NT type and even the DEs, but 1 gap speed DEs are much more common.
The zone blitz play (also know as a zone fire play) has been around for ages. Dick Lebeau took the play and turned it into a full system for Pittsburgh in the early 90's. He tried his hand at head coaching and being a coordinator elsewhere, but with little success. He doesn't seem to be a good manager, and isn't great at adopting to the existing systems of other teams. What Lebeau is know for it two things. His players love him (they play hard for him), and he is an excellent theoretician who develops elaborate plays with many twists.
The idea is that the different DLs will often drop back into coverage, while several linebackers (and even defensive backs) will blitz. The OL can't brace themselves, because if they do they will likely brace for the wrong assault. This is the one defense that prides itsself on turning the tables - the defensive line and the LBs hit the OL hard and often and try to wear down the other side.
CBs most often jam or jack the WRs , then either drop into zone or blitz. SAFs either zone or blitz (a safety blitz is called a "monster"), the LBs blitz most often, and sometimes zone, the DL either rushes or ends up in zone. It's a very fun defense to watch.
This defense tries to stop the run by penetrating the OL and disrupting the offense's backfield. They stop the pass by targetting the QB with heavy blitz packages. The zone blitz is very effective against screen passes, wreaks havoc against check offs by QBs (because the zones can't be anticipated, nor can the rush), and is the only major defensive scheme that is predicated on wearing down the OL instead of the OL wearing down the DL. For these reasons, the timing system used by many spread offenses can face more troubles here than in many other systems.
There is one glaring weakness. You drop a DL into a zone and the blitz doesn't hurry the QB and the QB has a quick-realease for an arm... well your defensive lineman isn't probably going to match a WR or TE going for a reception, is he?
Another scheme that makes the 3-4 so flexible is the Over/Under. In this alignment, the linebackers rotate can "rotate" or "slide" to the "Over" (towards the strong side) or the "Under" (towards the weak side). The rotating OLB moves up to the line of scrimmage and plays the "50" or "60" technique (adding the "0" means he is lined up off the line of scrimmage on the OT or TE outside shoulder). He can be in either a three-point or two-point stance. The two ILB's rotate to a "40" and "10" technique and the backside OLB now plays the "40" technique. While this alignment can easily be confused with a 4-3, it is definitely different. Either OLB can be in blitz, stunt or coverage. By moving the OLB to a "60" technique (slightly outside of the TE) it puts him in great position to either jam the TE, a speed rush, or coverage in the shallow flats. Also, the backside OLB can loop around the tackle for an outside rush or overload the weak side protection by blitzing the "A", "B", or "C" gap. The Over/Under also yields itself well to the zone blitz and makes it very easy to disguise coverages.
PASS COVERAGE
Coverages as defined by Wikipedia are:
* Cover Zero - Strict man-to-man coverage with no help from safeties (usually a blitz play with at least five men crossing the line of scrimmage)
* Cover One - Man-to-man coverage with at least one safety not assigned a player to cover who can help out on deep pass routes.
* Cover Two - Zone coverage with the safeties playing deep and covering half the field each.
* Cover Three - Zone coverage as above, but with extra help from a cornerback, so that each player covers one-third of a deep zone.
* Cover Four - As above, with the corners and safeties dropping into deep coverage, with each taking one-fourth of the width of the field. Also referred to as Quarters.
The effectiveness of a defense against short passes and the run generally drops as it goes from Cover Zero to Cover Four, while their effectiveness against deep passes increases.
These are basic secondary coverages that can be utilized by just about any defensive formation.
What makes the 3-4 defense so unique is that if the proper players man the defense, the extra LB allows more versatility in coverage. An extra athletic player in the lineup can be used to confuse QB's of where his coverage responsibilities will lie. For instance, in a 4-3 defense zone, its pretty common for the MLB to man the zone in the middle of the field. But in a 3-4 defense, either one of the ILB's could play middle zone, or for instance, a blitz could come off the edge and the extra LB could run to cover the blitzers area after the snap.
Its also common for this defense to utilize bracket coverage. Bracket coverages are prevalent in this defense due to an extra athlete on the field. Eight (4 LB's/4 secondary) versus losing the extra LB in a 4 man front. There are two types:
1. short/deep...also known as over/under where one player will attempt to take away any underneath patterns without fear of getting beat deep because he will have help. EX. When you see a LB lined up on a WR, he isnt playing him man to man, he's merely attempting to take away slant and curl patterns with help over top
2. inside/out...this coverage is when one player attempts to take away out patterns and sideline patterns while another player attempts to take away underneath inside patterns. EX. A CB on a slot WR will line up with outsided technique (outside shoulder of WR) only allowing him to release inside where a LB is waiting to take away slant patterns.
In addition, a popular coverage is the man-under zone. In this coverage scheme, you could have any combination of man to man match ups along with other players covering zones in the field. For instance, you could have your CB's locked-up in man coverage with safeties playing a two deep zone. This type of coverage allows defensive backs to play tight at the line of scrimmage to disrupt the receivers pattern. It also great for stopping the quick-out patterns and quick screens. The downside to this coverage is that you could have a LB covering a RB or TE in space. This is generally a mismatch.
The 3-4 lends itself into easily adapting to nickel or dime coverages. Replace a LB with a DB and you have a nickel. Replace another and you have a dime defense.
The 3-4 Defense is a great defense to run if you have a coordinator that understands how to bring pressure from all different angles. A prime example is the New Orleans game. This is the only game in which the 3-4 was run with success. Albeit only for the first half, but it demonstrated what the 3-4 defense can do to QBs. Drew Brees was flustered and we went up 24-3.