Well to those that did not have the honor to see him play, everyone has their theories on what made Marino so great, I believe it was a load of traits that made him who he was...
Quick Release:
Got to start with the most obvious. The way that he snapped a pass like a viper was a thing of Beauty. I do not know how many times I watched the pass-rush quickly closing in on Dan, I would be yelling get rid of it, and at the very last second, snap...completion yards away. He knew his ability, he knew he could wait that extra second to give his receiver that extra time to get open, and was not afraid to take a shot for it.
Toughness:
As I said up there, Dan was not afraid to take a shot if it meant making a play. Now a days someone like Brady gets hit, and he pops up crying he was hit too hard, or late...Dan would pop up with only one thing on his mind, did I complete that pass.
Touch:
This one surprisingly some fans did not notice abut Dan, but he actually did throw a very catchable ball. John Elway was without doubt one of the greatest QB to play the game, but early on (And at times during rest of his career), John tended to throw passes that almost seem to take skin from the receivers hands. Though Dan's arm was not Elway strong, but when he had too, he threw a very hard fast ball.
Dan knew when to throw hard, and when to just put touch on the ball. I remember me and my friends would marvel at how well he placed it, almost felt like one of us could be down there, and he could make us look good.
Confidence:
It is said, to be a good Corner, you have to have a short memory, with a QB it's the same thing, you make a mistake, you don't allow it to stick with you, you just go to the next play. Dan could throw two straight passes that are almost picked off, the next play the only option is someone double covered with a small window, and he will go that direction without thinking twice. Great QBs are never afraid to fail, though Dan would probably put it, he just doesn't believe he can fail when he sees the play.
6th Sense:
Ah, and here it is, the catigory where I talk about the infamous and very deadly one step. Dan was not fast or quick, Dan was not agile or that athletic, but what he did in the pocket made Fred Astaire and Gene Kelly envious. Dan had a sixth sense of when, and where the pass rush was coming from, and just as the D-Player is just about to grab Dan, that deadly one step to the front, back, right, or left, and suddenly Dan seemed miles away from the defensive players grasp. It was nothing less then beautiful to watch.
Intensity:
The personality trait that most defined Dan, and made him who he is. I always remember wondering if Dan's teammates at times disliked him, with the way he would rip into a players that made a mistake, but the answer is it didn't, though at that point it would probably anger whomever got torched by Dan, for the rest of the game that player more times then not played a better game, which made them better players.
Like Shula (Who ripped you also to shreds), they knew it came from driven men that refused to lose, which if you did not respect that, you did not deserve to be on that team. Dan was my much tougher on himself, then those around him, and like Shula, expected nothing but perfection every play.