I wasn't aware anyone ever questioned his heart. His leadership, toughness and willingness to put seems to be what he has always got high marks for.
Making quick, accurate reads seemed to be more what was questioned. I think that's been the big area of improvement for him. Seemed in the past he often took too long to get rid of the ball waiting for clear separation between his receiver and the DB, and now he is learning to understand the coverages and willing to throw the ball in a spot that gives his receiver a chance, but not the DB.
I have at times in the past seen his arm strength questioned, and he certainly doesn't have a cannon, but I think he's easily proven his arm is strong enough to make any throw he needs to.