I would believe Teddy Bridgewater. No reason for him to lie, exaggerate, or coverup...nothing to gain; nothing to lose. But I'm not holding that against Brady either. Let's assume it's true. He seems to have learned some things from that experience and is certainly running the Buffalo offense capably. So Brady had success with the Saints, jumped to LSU to run their national championship offense; went to the Panthers and got humbled; and is now with the Bills, seeming to have learned something from his Panthers failure.
Reminds of the Payton situation with NYG when Fassell stripped him of playcalling duties. And Parcells said Payton tends to "get the virus", referring to pass-happy offense. I believe that Fassell and Parcells both humbled Payton somewhat. But CSP seemed to learn from that experience, and got better for it. I'm not saying Brady is the next CSP. Maybe he is, maybe he isn't. I'm just seeing similarities in their career trajectories. I'm not holding the Panthers gig against Brady either.
Truth be told, I'd MUCH prefer a guy who took a hard punch and got back up off the canvas over a guy who's never taken a hard punch before. I know a LOT about the former; not so much about the latter. JMO...