4. David De Gea
It's a chilling indication of your problems when Massimo Taibi comes out in the press and suggests that he can see something of himself in you. That's the player widely recognised as one of United's worst ever Premier League era signings thanks to THAT howler against Southampton. And while it is somewhat cruel to suggest that Spanish 'keeper De Gea is anything like as poorly received as Taibi was, the big stopper is rather unfortunately hobbled by confidence issues (or so it seems) and can be prone to errors, which cannot be endured by a team of United's stature. Sir Alex has form with keeping errors after all, and though his custodian cost a big chunk of cash, he isn't invincible. Right now, United don't have the quality in reserve to really replace De Gea from within, and unfortunately the longer De Gea is questioned this season, the more his confidence could suffer. And goal is the worst place to have any kind of chink in the armour.