Chelsea were absolutely terrible but Wenger got it 100% right.
Starting off with Chelsea, defensively shambolic. The Terry-Ivanovic parternship was awful. Way too much space between the two and positionally can not work together. Ivanovic is not a centre back. On the attack, they produced nothing. They lacked a "spark". Anelka would've certainly helped, his link up play is excellent.
Considering how poor Anelka played recently, I'm not even sure whether he would make any difference if he plays.
Wenger made all the right decisions though. First off with Walcott who was absolutely brilliant. He pinned back Cole all game and nullified his threat, whilst also contributing with a goal and an assist. Then Diaby on for Walcott was what they needed in the centre, adding another combative player. However taking Walcott off meant that Cole was freed and was able to have an affect on the game. Wenger then brought on Rosicky though whose positioning is very good and was able to hold back Cole again.
Putting so much emphasis on the stopping of one player may seem strange, and looking into things to deeply, but Cole has been the most dangerous player Arsenal have faced when playing Chelsea in recent times. Drogba has scored the goals, but he finishes what he's given, and he's only given things when the likes of Cole provide it.
I agree there. For once, Arsene Wenger got it right as 3 of the last 5 goals(excluding the game yesterday) we scored against them came from Ashley Cole. Playing Djourou was perhaps a good move too considering Drogba wasn't really effective.
What Ancelotti did brilliantly last season was adjust his tactics to suit his most in form players. Chelsea played a diamond, christmas tree, then a 4-3-3 at different stages in the season depending on how well everyone was playing. Currently, they have a complete lack of cohesion in attack and aren't able to create chances. Defensively they've been awful as well but that isn't to do with tactics much - just the individual players playing badly.
Malouda is in pretty poor form, and Kalou is expendable. Chelsea should revert back to a diamond formation - at least temporarily. Drogba is being isolated on his own at the moment, and having Anelka alongside would be good because he links up the play - something Drogba doesn't do. The first team players that Chelsea have would suit the diamond midfield, but that's the problem. It's only the first team players, and playing the 4 main centre midfielders would mean that the bench would be even weaker.
We switched to 4-3-3 last season was mainly because the diamond formation have been found out and some players were ineffective in it. E.g Lampard. And I don't think playing the diamond formation would make the bench any weaker because I think Ancelotti will probably play Mikel, Essien, Lampard and Malouda in the diamond. Those four players would start anyway even if go with the 4-3-3. As for Kalou, he is just far too inconsistent and unreliable!