That's the point. Take away Rooney, Rvp and Vidic and your left with a very average, ageing squad. Rio is still a good player but his best days are behind him. Take a look at their midfield, Carrick, Fellaini, young and Valencia. Does that look like a title winning midfield? Even Tottenhams midfield is 10x better than that and they are aiming for top 4.
I said it a lot last year that united did not have the squad to win the league. It was SAF's ability to know how to win games that won them the league. Take him away and you're left with an average/ageing squad barring RVP, Rooney and Vidic.Their squad needed a major overhaul this summer IMO, they needed creativity through the centre of midfield and a couple of wingers who know how to beat a man.
Unsurprisingly, Moyes isn't exactly renowned for these type of signings and chased a DM and a LB. Herrera would have been a good signing but they still needed more. Look at City, Chelsea even Tottenham and Arsenals midfield and tell me it's not 100000x better than what United have. Cleverly is lucky to be playing for a top 10 team never mind the champions, same goes for young. Valencia I like as he works hard and can provide moments of quality but he's not good enough to be a regular for the champions of England. Carrick again I like but even he is 32 and isn't the player he was and will only get worse. Felli we all know is a good player and I think he will do well for united but the defensive side of their team isn't the problem.
Their midfield is so mediocre is frightening. They'll be lucky to get 3rd this year as the signings the other top teams have made are streets ahead of Uniteds midfield and without SAF's know how, they will suffer.