The offside is most certainly a fundamental rule. It allows pressure dynamics in the game and introduces intelligence as a performance factor. But it is also a part of the game that is extremely difficult to master. Every single situation in the game being so specific, how do you practice and create patterns to follow?
Well, it’s a delicate theme, but we can still try to help out with some general rules to follow.
Of course, it’s the main factor. Excellent communication between the defensive players is essential not only in the specific situation of an offside trap but in general. It doesn’t mean only that the players must talk all the time. (Try talking when a 20.000 crowd is pushing the team…you don’t hear the guy even if he is right next to you…) It means that the players know each other well, that the 4 of them acts like a unified line, that they sense the movements between them. For this communication to be effective, they must play and train together for some time and the coach has to introduce specific drills during the practice to put them into real situation. There, they can work on some coordinated movements and pay attention to one another. You need to know that in the game, the last player that decides whether to step out and use the offside trap does it in regard to the position of the other guys. He must make a decision and he has a BIG responsibility. Do the movement too late and the striker is alone against the goalkeeper. To summarize: in order for the offside trap to work, it needs coordinated movements between the players. The last decision is often made by one of the central defenders, who must be followed by his associated fullback.
This is a concept that is not always understood by the players, but defenders will know what I’m talking about. In order for the defensive line to play high (by using the offside trap to secure the space behind them), defenders need pressure being put on the opponent carrying the ball. Why is that? Ok, let’s say the defensive line is high. It leaves a large space behind it. If the opponent who has the ball is left without pressure, he has time to look up, think and adjust a long pass in the space behind the defenders, while the attackers make a run in that space. Defenders are static, the situation is impossible to control. On the other hand, if pressure is put on the opponent, he won’t see the runs, he won’t have the time to execute the long deep ball and he will have to choose another option, more safe (back pass or pass to the side). If there is no pressure, the defenders have no other choice that to cover more space and position themselves closer to their own goal. This also means playing with a lower defensive line…
It is a commonly known fact that central defenders are at their best when they reach the age of 30. That is because the experience they’ve gained. Having the ability to read the game is something that is acquired and using the offside trap is one of the things that you learn to do. As a defender, you often encounter attackers that try to escape your marking by making runs. Being able to see those silly runs and put the player offside is a very positive thing because it can stop 5 to 10 offensive actions of the opponent during one game. If the defenders always follow the attackers, they give them more opportunity to be dangerous. With experience, players simply get the ability to effectively choose between covering the player or putting him offside. Of course, covering is much safer and you want to use the offside trap only when the outcome is guaranteed at 100%.
It is essential to have a player in the defensive line who can lead the defensive block and give orders. When the ball is cleared away from the goal, one player has to command the whole group to go out and put pressure higher. If you stay around the box, the danger will come non-stop, by waves. If you have a guy that can shout and lead the line higher, it is a big advantage because it provides a constant organization. The tendency of some players working on their own is much lower.