I like Carr. I think he's smart, saavy and a team leader.
Chad Pennington and Mike Vick has both lead their teams to playoff games. So I'm not so sure they haven't accomplished anything.
So much depends on the team surrounding the QB. If it's not so hot chances are the QB will struggle no matter who it is.
I think it's safe to say that all 3 of these guys can and will play in many playoff games before they retire.