You can't surround world-class with mediocrity, at least rarely... Tevez had to put up with it in the first season of the Mancini-era. He single handedly dragged us into the CL and now we've failed to move forward. Dzeko and Milner the main culprits. People kiss their ass. Why? Good players in their own right, good attitude and both work hard... it's like the fat kid in PE, he's working his ass off, but he's still not on the same level of some other skinny kid who can merely jog and still be better.
Imagine sticking Jordan Henderson in the Barcelona side... it wouldn't happen as he's not on par with those around him, it destroys the side, not just in a physical sense, but also when it comes to player morale. Kolarov was another, though recently he's doing well to adopt to those around him.
Milner will always be chasing shadows though, despite working his ass off, he's out of his depth. As is Dzeko. It was the same under Mancini.
It really isn't all that difficult to see. Aguero, Toure, Silva, Nasri, Navas etc. are on a different level to Milner, Lescott, Dzeko, Garcia.
You can't teach them to do better either, some manage to evolve. Hart, Kompany, Richards, Zabaleta are all good examples of players who fit in perfectly. Milner was always a sad case as we never got the same Milner that Villa had and alot are in denial about that. Look at all the winning Champions League sides. Usually perfection all over the park, no passengers. Barry was the latest victim, great player in his own right, but just couldn't play at the same level as Y.Toure or Silva. It's like playing football on the park with the older kids, the young ones just play passenger and give it to the big kid because they can't match their potential.
I should stress that Dzeko, Barry, Milner, Garcia etc. are all great in their own right and the attitude all approach to the game is to be applauded. But there's a reason why young footballers all play against the same age level. U12s, 13s, 14s, 15s etc. It's exactly the same scenario, U12s can't compete with the 15s.
And it's not fair on any of the players. Milner works his ass off but can't reach the same or contribute the same as Silva. It effects both of their games and not in a positive way. Look at the team we started last week against United, it was all very level playing field:
Hart, Zaba, Kompany, Nastasic, Kolarov, Fernandinho, Toure, Navas, Nasri, Aguero, Negredo.
There is no weak link in that side, nor is there one in Barcelona's or Bayern Munichs. Take a look at their benches, all arguably at the same level as those in the starting 11. We've still got deadwood at the club.