I'm not questioning his work ethic, I'm questioning his talent. I'm not sure there is a precedent for a player fixing their motion when it got this bad. Let alone the other aspects of his game. I understand that Brady rebuilt his, like Tiger Woods rebuilt his swing. But those guys broke down a great motion and rebuilt a greater one. Every time people say "oh [player] will go from bad to good if he has an offseason to work on it" it just never seems to work out.
And if he has to devote all his time to his throwing, I'm skeptical that he can improve the aspects of his game that also need improvement - decision making, pocket presence, timing, etc.