Football / Soccer / Calcio / Futebol / Fußball

Sure, you can find some, but thousands of examples? I think it's far more often the case that the players that look to have gotten worse really aren't, they are just being expected to play at a level beyond their abilities so they look bad. For example a player having a great season in the Championship, getting sold to a PL team and doing poorly most likely isn't receding from their peak, they were never a PL level player to begin with.