The thing is that this wasn't a decline, it was a damn shame because he still has the ability to have won that fight. I think every sports fan is aware of the potential "advantages" of showboating, we're also aware that they are minor and its a stupid risk.
On Gretzky, Rangers weren't a bad team at the time and he got like 10 goals in the playoffs first year there. It was with the rangers that he broke Gordie Howe's all time scoring record, so these last years although he wasn't on the best team, he was playing very well (near top of the league) and his time with the rangers secured his legacy.