Does not have the Charisma to be a leading man.
He seems like a sweet enough guy but he can't hide the fact that he was raised by a single hippie mother who raised him like a delicate flower child and not a man. He never played sports, didn't have any brothers and never did things that most boys do which is why he's a pussy and does not have the balls to play a leading man.
Audiences are too smart to believe him as a super hero or someone like Pablo Escobar. In reality Turtle would make a better Pablo Escobar than this guy. All great leading men were raised like men and not like girls. Too bad his mother made no attempt to give this kid a pair of balls and there's no hiding it on screen. I wish him the best and think he does a decent job on Entourage all things considered.
Notice on Entourage all the times they have played golf you never see Vince swing a club or do anything physical for that matter and the reason is that he looks so pathetic doing it that they don't want to show Grenier looking like a girl when he's supposed to be a charismatic leading man.