Formation chart after the jump.
Responding to Gareth Bale. Bale's been recognised as a key element of Tottenham's attack all season, and ignoring him tends to lead to some rather dire consequences. Carlo Ancelotti's reply was to have the appropriate fullback man-marking him at all times - the job typically falling to Paulo Ferreira, since Bale prefers the left side. I suspect Ferreira would have started on Sunday even if Jose Bosingwa wasn't injured in the midweek game, since he's a better defender than his compatriot, but there really was no other option for Chelsea short of shifting Branislav Ivanovic wide and fielding Jeffrey Bruma in central defence. In addition to gluing Ferreira to Tottenham's marauding winger, Chelsea also ensure they always had someone in close support - typically Ramires, but occasionally Ivanovic. By and large, this strategy worked pretty well:
Figure 1: Gareth Bale's passing in previous six Premier League matches.
Bale attempted just 25 passes during the match, significantly lower than his previous five-game average of 40.2. His accuracy was also a shade lower than usual. Ultimately, despite a few flashy moments, the winger failed to have much influence on the match - perhaps the rather thorough kicking Chelsea players gave him in the early stages of the match made life a bit more difficult for him. However, the adjustments he forced the visitors to make to their system had some interesting repercussions, as we'll see shortly...
Strage players free. Chelsea's 4-3-3 was slightly distorted by the need for two players to be in close attendance to Gareth Bale at all times. As Zonal Marking pointed out yesterday, a 4-4-2 would see the right winger move back to double up on Bale, but that's harder to do in a 4-3-3, as Salomon Kalou was simply too advanced to provide much in the way of defensive support. Instead, Ramires, who was playing as the right central midfielder took the burden, drifting to the flank to pick up Bale. This left Michael Essien alone in the middle, and he was mostly preoccupied with nullifying Luka Modric. There was very little to Chelsea's centre, which had an affect on the forward line - Florent Malouda drifted to reinforce the middle and Nicolas Anelka ambled back and forth to very little effect. Anelka had been faovured to start due to his pace and movement, perhaps with the hope that having him lead the lines would force Chelsea to stop simply punting the ball long to Drogba, but he didn't respond with a performance that was anything close to effective, at least in the first half.
With Wilson Palacios broadly covering Malouda, this meant that Alan Hutton had a lot of space at right back, and Ramires was generally free when Chelsea was in possession, which lead to some interesting combinations with Kalou down the right. Benoit Assou-Ekotto was magnificent at left-back however, racking up a whopping ten interceptions in an amazing defensive effort to more or less cut out Chelsea production on that flank. Spurs had some joy down Chelsea's left, however - Hutton was in plenty of space and pushed very far forward, which often let Aaron Lennon scamper past Ashley Cole, who was doing double duty on defence. Hutton's expeditions forward came at a price, as whenever Malouda was isolated against him he didn't fare particularly well. Most of Chelsea's thrust in the first half came from areas of the field he should have been defending but wasn't.
Spurs score. Bale might not have had a direct impact, but he was able to draw Chelsea out of position by playing in a more withdrawn role than usual. With Ferreira up the field marking the winger, space was open for one of Tottenham's strikers to occupy. Jermain Defoe was the man to pick up the ball at right-back, and he drew the attention of Ivanovic and (sort of) Ramires. This left John Obi Mikel as a make shift centre half after Defoe had amused himself by dragging the Serbian all the way back to midfield, at which point he passed to Roman Pavlyuchenko in the box. At this point, Mikel made an elementary error - which is to be expected, since he's not a centre back, and the Spurs man took advantage of it to score. The anti-Bale defence ultimately led to an unfavourable matchup for Chelsea, and resulted in a goal. This isn't really a criticism of the tactic itself, since Bale was shut down and we don't know what would have happened had Chelsea not focused so intently on stopping him, but it is interesting to see how focusing on one area weakens you in others.
Chelsea switch to 4-2-4. With Didier Drogba starting on the bench, Chelsea had a way of switching things up at the interval, and they did so by removing John Obi Mikel for the striker. Mikel hadn't really had much to do. Without Rafael van der Vaart and with Modric increasingly stifled by Essien, most of Tottenham's threats came from the wings, and Mikel was reduced to vaguely following whichever Spurs striker felt like sitting deeper at the time. When Chelsea were in possession, Mikel was in turn picked up by a striker, neutralising the visitors' numerical advantage in midfield.
When Drogba came on, Chelsea left Essien and Ramires to boss midfield and instead went with a highly-mobile four-man attack. Anelka was dropped deeper, occupying Wilson Palacios, and with Drogba taking up the attention of the centrebacks it left the wingers isolated against Tottenham's full-backs, which was a dangerous situation for the home side, especially when Malouda squared off against Hutton. Chelsea dominated the game after half time, and it was mostly thanks to the formation change giving them a more stable attacking platform. It also had an affect on Tottenham's attacking play. Says Zonal Marking:
In dropping onto Mikel when they were out of possession, [Defoe and Pavlyuchenko] had a fairly easy job. But when they were asked to retreat much deeper to pick up either Ramires or Essien, the striking partnership broke down completely, especially considering that Chelsea dominated possession in the second half, so Spurs were almost permanently playing a striker in the centre of midfield.
Passing. Last week I added a quick graph to show how thoroughly Marseille dominated Chelsea in term of passing, and the result here is just as interesting:
Figure 3: Passing for Tottenham and Chelsea, 12/12/10. Powered by Tableau.
Michael Essien played 91 passes, only seven fewer than Luka Modric and Wilson Palacios combined. Chelsea attempted almost 600 passes compared to Tottenham's 378, and they were also significantly better at completing their passes (79% vs. 73%). Essien, Ramires, Terry, and Ferreira (who had a good game, again) each had more complete passes than any Spurs player, and Mikel, who played 45 minutes of the match, would have ranked fourth in Tottenham's completed passes table had he been playing for the opposition. Strong passing numbers aren't everything - Chelsea didn't do a very good job of being incisive by any means - but they had the ball a lot more than the home side, and definitely deserved to get something out of the game.