West Ham’s defensive block
When Chelsea had the ball, West Ham took up deeper positions in their own half. They often prevented Chelsea from gaining a numerical advantage against their backline with this deeper setup, while also having cover through the wide players dropping and support from the central midfielders.
They wouldn’t apply collective pressure from the front, as they would maintain numbers in midfield and at the back—where they could pressure forward passes and have support around them to cover for potential mistakes. Lanzini and Noble would move up to close down Cesc and Kante, preventing them from receiving the ball facing play or being able to turn; Carroll could move to apply some pressure to Chelsea’s back three, but mostly remained on the inside to block the pass to Luiz when Cahill had the ball; Feghouli dropped to follow Alonso; Snodgrass would go between dropping back to follow Moses and moving up to press Azpilicueta; Obiang was usually spare to shift to either side as cover while also pressuring Costa; and Kouyate would follow Hazard as he moved deep to look for the ball from Cahill.
Fonte (mostly) and Reid could move up to follow Costa and pressure him on the ball, but when Snodgrass moved up to press, they had some issues in covering Pedro’s movements towards the ball. As a consequence of Snodgrass moving up to Azpilicueta, Cresswell would switch his attention more towards covering Moses, while Pedro receiving the ball deep could be too much distance for Reid or Obiang to get close enough to him. Lanzini dropping from Cesc allowed them to get someone around Pedro receiving the ball, but that would result in a lay-off for Cesc, now facing play and out of pressure, to play forward passes and push West Ham back.
But, for the most part, West Ham were successful at preventing Chelsea from creating chances. Pressuring from the back in numbers prevented Chelsea from breaking their lines and the numbers behind the ball also limited Chelsea from successfully increasing the speed of their possession after forward passes.
When Luiz was able to get the ball free of pressure at the back, he attempted a few long passes behind West Ham’s backline, as well as a forward passes to feet for Costa, but in general, Chelsea were unable to get the ball up to West Ham’s backline. As a result, Chelsea’s front 3 began moving deeper for the ball outside of West Ham’s midfield line. The best situation they were able to create during these moments was when Pedro moved over to the left to overload. Kouyate stepped up to him, allowing Hazard to be up against Fonte with space behind on the last line.
While Chelsea were having some problems breaking down West Ham’s organised defence, they were able to create various counter=attacking opportunities from deep defending and defensive set pieces.
Courtois’ quick, short distribution created some of the counters—rolling the ball out short (underarm) to a player facing play to start a counter is much more beneficial than long (overarm) throws, where the player may receive immediately under pressure and have to judge the speed of the ball (while sprinting forwards) in order to control it.
West Ham with the ball
West Ham played long from goal kicks to Carroll in the air, with the midfield three behind him and the wingers moving beyond for the second ball. The support form behind was aggressive in pressing for the second ball; when they recovered it in deeper areas they would quickly play forward again.
When they had possession in open play inside their own half, they were able to keep the ball through the numbers they had at the back and outside of Chelsea’s block. They tried to either progress up the wings or play long balls forward when they were under pressure and had limited options.
Cresswell would move up early on the left, while Lanzini and Obiang filled his vacated space to show for the ball. Noble could move deep or forward for the ball or move wide in order to support progression of the ball up the wings. On the left, Snodgrass would move inside on the last line, while Feghouli could drop deep on the right to receive the ball outside of pressure or he could go between Chelsea’s lines to receive the ball ready to dribble diagonally inside.
The reason for West Ham’s focus on advancing up the wings was to create opportunities to cross into the box through Feghouli, Cresswell and Snodgrass. The crosses were aimed for Carroll to attack the far post—but Chelsea’s defenders did excellently in the air to win the ball against him.
Second half changes
Upon Matic joining the game, Chelsea changed to a 3511 and caused organisational problems defensively for West Ham. Cesc was able to find freedom on the ball facing play in order to play forward passes, while Kante and Matic could open up the midfield by moving wide to receive the ball.
With West Ham chasing the game and Byram moving up high on the right more often than Kouyate in possession (allowing Ayew to move inside and between lines for the ball), they were left slightly exposed at the back when they lost the ball centrally, and Chelsea were thus able to create some good situations for counters (but failing to take advantage).
While West Ham were able to frustrate Chelsea’s possession, Chelsea continued to find solutions from other areas in order to create chances—through counters and corners this time. Chelsea did exceptionally well to prevent Carroll from getting chances from crosses, as well as limiting West Ham’s chances from corners despite their abundance of strong players in the air, which resulted in Azpilicueta marking Fonte on corners for example.