As requested by Andyyyy:
Chelsea use the tallest players in the box as the runners: Matic, Luiz, Cahill, Costa, Alonso. Hazard, Pedro or Moses can take them (in that typical order of frequency), while Willian and Fabregas were most used when in the starting team.
The players outside the box vary based on the taker of the corner and the amount of players the opposition leave high. Azpilicueta is always back, even when the opposition don’t leave anyone forward, and Chelsea always seek to maintain this one man numerical advantage. For example, when Leicester left two players forward on their defensive corners, Kante and Moses moved back to compensate and maintain the one man superiority.
There have been a few routines used at offensive corners. The most noticeable has been Matic consistently moving ahead of the first post to flick the ball on to the second post. This has been used against all types of defensive marking to good effect, with Costa scoring twice in recent games from this exact move.
The movements of players other than Matic can change. Cahill, Alonso and Luiz can make first post runs ahead of Matic to also flick the ball onto the second post.
When Chelsea have a numerical advantage on the edge of the box, they can exploit that with either a short corner or a direct pass to the player on the edge. Hazard has often been the recipient of these corners, where he is able to shoot first time. Below is an example of the routine used against Manchester United where he was able to have a shooting opportunity.
Another change in this corner, as well as some corners into the box, is Luiz moving to anticipate the pass if it goes too far. He has made movement away from the opposition marker on a few occasions inside the box when he is in these areas, such as on the volleyed chance against Everton. On another occasion in the game against Manchester United he received the ball free in space on the second post before shooting.
One last routine that has been used is a quick and short corner to Hazard, where he will try to surprise the opponent while they are disorganised.
During defensive corners Chelsea make one switch to the group that is used to attack corners inside the box, with Azpilicueta is used as a man marker and Costa now used as a zonal player instead. Hazard generally stays forward.
Kante and Pedro (or Willian) are responsible for the quick reaction to short corners; there is delayed support from Moses while Costa maintains his zonal position on the front post.
Moses and Pedro can also be more variable in their marking—they can remain close and mark players on the edge or if the opposition use extra players inside the box.
Courtois can move out for the ball, where he can make use of his height to either punch or catch the ball. He can then use the ball quickly to launch counter attacks.
The zonal players, along with Hazard, are quick to react to winning the ball—where they break forward for counter attacks. Hazard can receive the ball and hold it until he finds support. A prime example of this is the Moses 1-v-1 chance against Leicester.
When Chelsea make substitutions, they are almost exclusively the zonal players. This allows them to easily take up the zonal positions without needing to re-shuffle the five marking players, as well as having the fresh legs among the players used for counter attacks.
Offensive free kicks
For offensive free kicks Chelsea have a few designated takers from different positions. With free kicks from the front, David Luiz can shoot directly. Pedro will then be behind the wall to react to the second ball—Alonso is another who anticipates the second ball. Cahill is also behind the wall, as he attempts to block the keeper’s sight of the ball, before moving into the wall to disrupt it.
For wide free kicks, Chelsea have recently used Alonso, Hazard and Pedro but are missing the quality of delivery that Willian (and Fabregas) offer in these instances.
Alonso has the best delivery from these situations, but then Chelsea have one less tall player inside the box—David Luiz and Azpilicueta are kept back.
Another option Chelsea have used for wide free kicks is to play short, with overloads around the ball in order to progress up the wing if possible.
Defensive free kicks
On defensive free kicks Chelsea have 6 players drop back into the box to compete for the ball—they are a zonal line, but they also use contact and marking inside the box. Kante and Moses maintain their positions and can support the second ball around the box. Hazard can remain higher up or he can join Pedro in the wall.
Along with Kante and Moses, Pedro and Hazard are also ready for counter attacks.
On the left, it’s a reverse situation with Hazard in the wall, with Pedro in support if the kick is taken short. There’s additional support from Kante in wide areas, while Moses is in a higher position to use as an outlet if Chelsea win the ball.
Less effective was the setup for a free kick from a central area that was used against Southampton where the Saints were able to get a free shot on target. With just three in the wall, Southampton had a player push Costa to move the wall and open a clear shot on target.
Quick free kicks from deep and kickoff routines
From deeper positions, Luiz can signal to Costa or Pedro when approaching the ball, before playing a quick and long free kick into the box. Quick and long free kicks to Costa may seem familiar, as they are something that Chelsea used effectively in the past—when Cesc was the player taking the free kick.
Lastly Chelsea use these long passes from Luiz during kick-offs as well.