It's pretty obvious Giggs, Rooney and Valencia are key players - especially Giggs who tends to provide a quality contribution when the team really needs it. Valencia releasing Nani on the right has been a revelation for him and for Utd, as typically Valencia was the player which Fergie would play when he wanted more defensive cover on Nev/Rafael.
As an Arsenal fan I keep forgetting we actually have RVP in the squad, as he's injured so often, but obviously in modern-day football the entire team needs to be able to attack and defend and take goal-scoring chances. Every player is much more key to a result now than in the past, so I don't think single injuries are much of a problem if the rest of the team can cling onto some form.
Obviously Utd losing Nani and Fletcher is a loss of two very solid players, but perhaps it's a chance for Obertan/Gibson to grab a few more matches and the reserves (Macheda isn't really a winger, but I think Hernandez had a lot of wing-time at the WC?) to step up. If you can't win except with your first XI then you arn't going to win a title.
