Silva was dire in the world cup, replaced in the first game, pretty much not to be seen again by Navas, who couldn't actually get a cross anywhere within the 18 yard box, then Pedro, who doesn't cross or pass in general. If Silva was "that" good, he'd have started most of the games, considering he started the first game with it as his slot, with barely any competition and was bad enough to be almost entirely dropped, I think he had a couple short sub appearances later on.
Yaya is very good, the only reason he was dropped at Barca, was he wasn't Spanish. Look up Henry's stats and name another reason that the previously, essentially hasn't scored or played or done anything Pedro, Keita and a few others were instantly promoted ahead of him. Henry scored like 30 goals in all competitions in the year they won the Champs league, the league, and 58 small cups of various types. Henry was outstanding that year, Yaya was decent, and both were benched for players who weren't even close to proven and both who aren't anywhere near as good.
Saying that, Yaya isn't the best in the world, at any role really, but he's leagues ahead of a washed up Vieira(who has been for 5 years), Barry, and Kompany/Zabeleta/couple others who can play a similar role. He's also leagues ahead of anything Arsenal have so I'd have loved it if he came, but I can't imagine Toure was full of praise of a manager who can't find any success anymore even if Toure wasn't at City but had gone abroad I don't think he'd have recommended Arsenal to his brother, Wenger basically crapped all over Toure in his final 18-24 months.
AS for Arsenal, we're way worse than we were before, Sol, well he's not actually that old so talking about his ability to hit 38 games is silly, firstly he wouldn't be required to and secondly, he's never once show he can't. Sol as backup is a huge step up from Djourou as backup, the later who can look good against crap preseason teams but is the type who gets very easily flustered when rushed and also is weak and not very fast, slow to react and just not very good. Gallas, was out best defender but playing like someone who was fed up with a losing team, a losing manager and being crapped on by Wenger aswell.
We've got 2 CB's, and no adequate cover, Nordtveit might be decent there in the future, and played quite a lot last year, but I can't see him being good enough yet.
AS for Gallas not having friends in the team, its a professional team, its not playing with your mates down the park. Do you know anyone at any job who refuses to do their job well because theres someone they don't like in the office, they do a job, and they don't have to go for romantic walks in the park after. Theres MANY players out there who have won everything alongside people they completely hate, Sheringham and Cole comes to mind, couldn't stand each other, didn't matter in the slightest.
AS for Boateng, he was actually pretty awful except in the last game, midway through the last game he seemed to work out what he was actually doing at left back and started to play pretty well, throughout the rest of the games he was quite easily "done", was pretty awful getting forwards, and he was almost constantly out of position.