This is all about defending in small numbers where it’s common for one or two defenders to find themselves in situations where they are exposed to an overload of attackers. MORE
Drop off is a delaying tactic used when a team is defending against a fast attack, or a counter attack.
When opponents launch a quick attack and have time to run at defenders, the defenders must drop off to reduce the space behind them and buy themselves time to squeeze together and reduce space.
This tactic enables the team to get into a good defensive position and decreases the danger of conceding a goal.