I'm a little busy with work to look for it now, so maybe I'll come back and edit this later and provide a link, but I read a study done last year or the year before that showed how, when trailing, QBs that have a high percentage of comeback wins, such as Brady, Manning and Mahomes, change their profile of passing and start attacking the intermediate/deep part of the middle of the field much more aggressively, because generally that's where you'll get chunk yardage out of a bigger variety of concepts (assuming teams are protecting the deep sideline shots with a lead). It just happens that the intermediate/deep middle is where you need the arm strength to fit balls into tight windows, and I do fear Mac's lack of comeback ability might be a function of that. He throws beautiful touch sideline fades, but those work when defenses are playing up and leave guys in man coverage. If you're down in the second half, no one will give you that throw as a freebie.