I wouldn’t say Manning has bounced around at all. He spent most of his career under Dungy, and when Dungy retired he was replaced by his QB coach. So that was all the same system, which boiled down to let Peyton call his own plays. Now he’s in Denver but the system still seems to be let Peyton do whatever he wants.
The problem is the self coaching player will eventually be out coached by a full time coach. Which sets him up for falling apart, because he’s got nobody to fall back on. If you put Peyton’s work ethic and smarts with a team that actually coached him he’d probably have 4 or even 5 rings. But somehow or another all his coaches seem to not want to do that.
I think Manning lacks big game instincts. I won’t say he chokes, but he often comes up small, and you can’t coach that.