A new offensive system will make a difference but I disagree they have a similar skill set. I don't think Brissett is nearly as accurate on the short and medium routes (especially between the numbers), he presnap reads aren't as accurate and he's not as effective as a scrambler. Whereas QBs like Brady and Manning and Rogers and Roethlisberger and Wilson see to play better when the game is online, JB seemed to want to do too much and on more than one occassion had a bad play that was part of costing the Colts a game.
He (JB) does have a strong arm, has a great deep ball and can throw that 8-12 yard out as well as anybody. He is also more of a risk taker than Luck which can be good and bad.