In the modern game, pressing has become a common defensive tactic in which teams apply immediate pressure on the ball the moment that it is lost. In theory, this is the when the team in possession is most vulnerable to turn the ball over again. Swarm the ball carrier is an excellent drill for players to work on aggressively pressing the opposition in numbers and trying to win the ball back quickly.
To prepare this exercise, build a square or rectangular grid with each side between 10-15 meters wide. One attacking player starts in the middle of the grid with two teammates on either touchline. In addition, four defensive players start in each of the corners of the grid.
The exercise starts by the coach playing a ball into the offensive player in the middle. As soon as the pass is made, the four defensive players on the outside run towards the attacker and try to win possession of the ball. If the defenders are able to win the ball or force it out of play, then they earn a point.
The offensive player can earn a point by successfully playing a pass to one of his teammates on the outside.
This exercise teaches defensive players to agressively pursue the ball while at the same time closing off passing lanes to isolate the attacker. Speed, teamwork, and communication are important for the defending team to take away the ball carrier's options and try to win the ball back.
The difficulty of this drill can be modified for the defending team by having different numbers of offensive players around the outside. For example, having only one passing option makes it easier for the defenders while having four offensive players on the outside makes it more difficult to stop.
Another variation of this game can be played by awarding the offensive player a point if they can retain possession of the ball for certain amount of time rather than trying to play a pass to the outside. This variation emphasizes the speed of the press rather than closing off passing lanes.