I'm saying mobility is not the key reason why QBs take sacks or face pressure. It's more how long they hold on to the ball and how quick they go through their progression. Generally, more mobile QBs get sacked and face pressure more than the pocket passers anyway. Dan Marino, Peyton Manning, Drew Brees and Tom Brady are all in the top 10 all time in lowest sack rate and it's not because they had good mobility. And it's not all the o-line either. These guys very consistently almost never got sacked.