The thick skulled prioritization of the left tackle continues to be a litmus test on progressive thinking about the NFL. Times have changed. In the old school NFL, offenses were "right handed". Most tight ends were in the mold of a third offensive tackle and they lined up to the right, which meant running plays tended to go to the right. Those same tight ends -- lumbering and slow footed as they were -- also often stayed in to block on most pass plays. Combining those two factors -- an emphasis on run blocking with help being offered on pass plays -- meant the template for a right tackle was a physical, road grader type who could get away with having mediocre feet.
But that's not the NFL anymore. First off, NFL teams are no longer predominantly right handed in the running game. Football Outsiders tracks this. The splits for running direction in 2015 were
Left end: 11%
Left tackle: 13%
Center/guard: 53%
Right tackle: 13%
Right end: 10%
http://www.footballoutsiders.com/stats/ol
There's a chicken and the egg argument to be made about whether the "right handedness" of the running game has ended because the modern tight end is an athletic pass catcher rather than a blocker or whether the switch to that kind of tight end is what stopped the dominance of running to the right. But either way, it's ended. And the league-wide hunger for that type of pass catching tight end also means that most tight ends no longer stay in to pass block, which means that right tackles are now just as much on an island as left tackles.
Defensive coordinators have been much quicker to react to this new paradigm than offensive coordinators and front office people, who continue to value left tackles with top 10 picks and right tackles far later in the draft (and in free agency). That's why you see many of the premier pass rushers in the modern NFL rushing from the offense's right. Guys like Von Miller, Khalil Mack, JJ Watt, Carlos Dunlap and our own Cameron Wake rush predominantly from that side.
And if that wasn't enough the NFL is now also a short passing league. Bubble screens are the new sweeps. Quick throws to slot receivers the new halfback dive. On those plays there isn't even time to rush from the outside no matter how fast you are. That's made interior pressure even more important than outside pressure. Dick LeBeau was one of the first to realize this and pioneer the double A gap blitz, and the variability an odd numbered front offers you with bringing pressure is part of the reason why odd fronts have made a big comeback. Those pressures -- identifying them and dealing with them and being able to make shotgun snap after shotgun snap while being blind to what you're doing -- is why center is the premium offensive line position today.
Interestingly, the importance of pass rushing athletes at defensive tackle (to combat the quick passing game) has also led to a decrease in the quality of offensive guard play throughout the league. Not that long ago guards were considered worthy of top 10 selections. People forget that John Hannah was the fourth overall pick. John Elway was traded in large part for a guard, Chris Hinton, who had also been selected #4 overall. Some of that has to do with the decrease in "power" schemes that utilize a pulling guard on snap after snap. But a bigger reason for the shift is the selection bias taking place in the high schools and colleges. These days if you're a very good athlete but not the prototype of a tackle or a defensive end, very few programs will make you a guard. They'll make you a DT. In other words, it's not that there are no more Chris Hintons or John Hannahs, it's that those men would have been made defensive tackles today, just as Ndamukong Suh was. That selection bias has made the guard play throughout the league absolutely horrible. Of the 64 starting guards in the league, perhaps only half of those are worthy NFL starters.
Eventually offensive coordinators and front office people will catch up to these trends and scale back the value they place on left tackles and scale up the value of the other offensive linemen. I wish we were smart enough to get ahead of the curve, but the concrete bullheadedness of received wisdom remains strong.