Figure 1: Chelsea at West Ham team starting formations. Chelsea in blue, West Ham red.
We've become accustomed to Chelsea's 4-3-3, but this is the first time it's come up against a 4-man central midfield, at least in the first half. West Ham lined up in a midfield diamond, packing the centre against Ramires, Michael Essien, and Jon Obi Mikel, but ceding the wings to Ashley Cole and Paulo Ferreira. Obviously, Avram Grant was worried about Chelsea's potential straight down the middle, and his team was certainly lined up to stop pushes through the heart of the pitch.
Without Florent Malouda and Frank Lampard to link up with down the left, Ashley Cole's surges forward weren't having quite the same effect as we're used to. Salomon Kalou and Ramires both did well in offering themselves for passes and trying to set Cole free behind the defence, but they lack the chemistry that the regular starters have built up with the England left-back and seemed to slow the pace of the game down on that flank. Ferreira, meanwhile, was having to deal with his own deficiencies on both sides of the pitch while trying to link up with Nicolas Anelka, whose touch was poor all game. West Ham's Victor Obinna was used for much of the match as a roving support striker, and his presence on the right kept Ferreira pinned back - not much was going on down that side, from Chelsea's perspective. However despite fairly good defending in open play on West Ham's part, two set pieces resulted in two Chelsea goals very early.
Half time brought a change in shape for the Hammers: Luis Boa Morte, who alongside Scott Parker had done very well in keeping Chelsea quiet in open play, was withdrawn for Kieron Dyer, a wide player. He was fielded mostly on West Ham's right, where he came into direct contact with Ashley Cole. This essentially switched the home side's formation to a 4-3-3, with the central midfielders staying home and marshalling Chelsea's second band while Obinna and Dyer tried to keep the fullbacks occupied.
Figure 2: Chelsea's passing in the 1st half compared to the 2nd, 9/11/2010. Courtesy Guardian Chalkboards.
As you can see from the chalkboards, the gambit worked pretty well in stemming the steady stream of attacks that had come down the Chelsea left in the first half and put West Ham in the driver's seat. Chelsea's midfield three were able to push higher up in the second half, but with the entire front band having a relatively poor game this didn't really do much for them - it wasn't until Gael Kakuta came on late in the game that Ramires or Essien had a reliable passing outlet higher up the pitch. Unfortunately for West Ham, the Chelsea defence played very well, especially John Terry and Petr Cech, which meant that at no point were the Hammers looking really capable of getting back into the game. Chelsea were finally able to capitalise on their midfield superiority (in talent if not in numbers) in the 83rd minute, when clever interplay between Ramires and Mikel set Ferreira free on the right to cross for Michael Essien, but West Ham replied with a clever volley from Scott Parker and a point-blank header from Frederick Piquionne that should have found the net.
Ultimately, Chelsea's early lead handed them the game on the platter. West Ham's attack vs. Chelsea's defence was always going to be something of a mis-match, but the home side did a very good job of chasing the game without opening themselves up for the counter-attack. One suspects that it would have been a different match entirely if Chelsea weren't 2-0 up 20 minutes into the game, but with Florent Malouda and Yossi Benayoun held in reserve the Blues could have made some changes to grab a late winner had it been necessary. The game was most interesting for seeing how an under-strength Chelsea performed against two different shapes, and of particular interest was how easy Ashley Cole was to nullify. After being the most dangerous player for most of the first half, Dyer forced Cole to sit back and defend, taking a lot of width out of Chelsea's play. This wouldn't usually happen with the starting XI - Lampard and Malouda tend to take the pressure off the left side by making runs in that area, but Kalou just wasn't capable of or interested in exploiting that space.