Sometimes it’s about reps. In the Shanahan offense QBs aren’t required to throw outside the numbers or down field much. Since the team strategy is to be a frontrunner—ball control leading to leads, leaving opponents to play catch up and deal with pressure from their pass rush—Garropolo and Purdy don’t have a lot of down field, outside the number reps.
McVay’s offense will provide those reps. You practice what you play and Jimmy G. will get these types of reps and, I imagine, have better results in that part of his game.
We Not Me