I think trying to identify a single area where it all went wrong is the wrong way to go. I know we'd like it to be just one area, because if it were then it would be dead simple to fix it. So I do understand why we'd all love to say that it was down to effort, or just down to Hibbert etc, but the truth us we are a long, long way from being as good as Chelsea. Even with Jags, Yak and Arteta, we are a long way off. We have to accept that all over thep pitch, we have players who are very good but not top class - man for man, we lose just about every matchup. Even if we swap, say, Osman for Defour, we are still losing at least 8 of 11 matchups against Chelsea, and debatably all 11.
However, we are already at a stage that we can beat the likes of Chelsea in these games. Not consistantly, but maybe 2 or 3 times out of 10. Let's not forget, we beat the [Poor language removed] this season, could easily have beat United at home, and should have beat Arsenal, 2 draws against Chelsea. We need a little luck to go our way, but that's all. Three years ago we'd have needed a miracle in these games, and we'd lose 6 or 7 out of 8 league games.
If I were to identify one area where we are lacking though, it's an area where we actually aren't doing anything wrong, but rather aren't even attempting, and that's actually winning the ball in midfield. At present, we are happy to stand in front of the opposition in a organised formation, hard to break down. This allowed Chelsea to dominate possession - in that heat, I'm sure we were knackered defending, which is why we had no energy to push on when we needed a goal.
Meanwhile, when we had the little spell early in the second half when we had the ball, Essien, Lampard and Mikel were sniping at us, never giving us time.
The game kind of reminded me of England vs Brazil in the 02 world cup in the heat of Japan. Brazil had the ball all the time, England kept giving it away and had to chase after it. At the end of the game, England needed a goal but had nothing left in the tank, and never even looked like scoring.
So, though I do agree than Osman and Hibbert are the weakest area of the team, I don't agree that replacing them with better versions are the best way to improve the team. That would mean playing the same way we are now, but slightly better. Far better, IMO, to find players that add a new dimension to our team (which, for all his flaws, Fellaini certainly did) - meaning a ball winner and some pace