Arsenal came into the game with many absentees to their sides which led to Arsene Wenger picking a line-up which featured Santi Cazorla on the flanks for the first time in a major match this season and ultimately affected their performance.
The Gunners were missing Mikel Arteta, Alex Oxlade-Chamberlain and Lukas Podolski due to injury while Gervinho was unavailable because of the African Cup of Nations. That left Wenger with little choice in terms of wingers, and it affected his pairing in deep midfield as well.
He had two choices out on the left - Cazorla or Andrei Arshavin; he chose to shift the former in from this usual central position, which meant that Wilshere pushed up from being a deep lying midfielder to take up Cazorla's usual role.
Being the away team, Wenger chose to the conservative route in defensive midfield and had Coquelin and Diaby sitting deep in front of the defence, rather than have Aaron Ramsey, who would have been more adept in pushing the ball forward, in the line-up.
As for Chelsea, Rafa Benitez had little choice in the middle of the pitch with David Luiz nursing an ankle injury and Jon Obi Mikel called up for the African Cup of Nations.
A contrast in deep midfielders
Chelsea dominated the first half and it can be chalked down to the difference in the two side's midfield intent.
Arsenal had Coquelin and Diaby sitting in front of their back four, with Wilshere tracking back to help put on Chelsea' trio of attacking midfielders.
It was a useful idea to nullify Chelsea's potent forward line, but it caused a big gap in midfield which led to Chelsea dominating the game.
First, the Gunners found it hard to catch Chelsea on the break as they were too far away from the forwards when they won the ball. Chelsea made the transition from attack to defence quickly, so it meant that Wenger's men frequently had to get past five midfielders right after they won the ball.
It also didn't help that Cazorla was shunted out wide in this game - he thrives as a winger when his team is laying siege to the opponent's box and lacked the speed and dynamism to play as a winger in the counter attack.
In this case, Cazorla was effectively taken out of the game by his team's strategy.
Also, Lampard and Ramires were given too much time and space to work with as there was little pressing from Arsenal high up the pitch, with Ramires in particular shining in the first half having won the ball that led to the build-up to both goals.
He was actually rash on the tackle and was lucky to not have been called for a foul for the first goal, but it showed that he had time and space to read the play, run from deep and stop Arsenal's attack.
Chelsea were targeting Arsenal's right back as a weak link in the match with most of the play going down that flank.
Sagna was fine holding his own on a one-on-one situation but his awareness was poor and he was not wary of player movements around him.
The first goal was an obvious example of Sagna's lack of awareness - he was tracking Oscar and wandered too high up the pitch, allowing Mata to easily slip in behind on goal.
To make things worse, Sagna was poor on the attack as well. He bombed very far forward to help Walcott on the overlap but had zero crossed completed, and failed to track back when Chelsea counter attacked. It can be seen in the 35th minute when he was slowly jogging back after hitting the ball straight at Ashley Cole, who was launching a Chelsea counter attack.
It wasn't helped by the fact that Walcott stayed high up the pitch and didn't provide Diaby a quick outlet forward, which led to him being caught on several occasions.
The statistics also backed the story here - Ramires had nine tackles and three interceptions in the match, the most of both categories, while Oscar and Mata had five tackles each, a surprisingly high amount for attacking players.
The Gunners came out of the second half a wholly different side, which was surprising given that there were no substitutions made.
Wenger simply pushed the midfield line up and told Cazorla to tuck into the middle of the lane. This took away the space and time Chelsea were used to and provided and extra option in midfield by getting their best player involved.
Arsenal's goal right after the restart was a summary of their intent - they won the ball off Torres early on, Cazorla cut in to play a through pass (his first active involvement in the game) and Walcott finished the move.
The changes they made later on served only to reinforce the area higher up the middle of the pitch, with Aaron Ramsey coming on for the injured Coquelin, Arshavin coming on for Diaby while Wilshere shifted into the middle.
This inevitably left them prone to the counter attack, but it was a worthy trade-off, sacrificing some stability at the back for control of the match.
Chelsea fans would be right to be concerned that they threw away control of the game after surrendering a 2-2 lead against Southampton. Benitez does not seem to react well to changes in strategy midway through the game (something Brendan Rodgers, in contrast, does well).
Wenger similiarly, could have reacted better when changing his side - he could have made the same changes midway through the first half, rather than wait until half time.
Perhaps more ominously, the match also showed how much they missed Mikel Arteta's calm passing and ability to stretch space in midfield.
Kelvin will be analysing a Premier League match every week in Tactics Watch. You can reach him by following his twitter account @plevyakin for more tactical insights and football updates.