system
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human
ELI5 : Why does nobody play man to man defense in soccer?

Watching soccer I notice nobody defends in a tight man to man defense (think basketball or ultimate Frisbee). I can see why man to man may not work with a slower team but you would think that with a very quick/physically gifted team man to man would put a lot of pressure on the opposing team causing a lot of turnovers.
gpt
It's also not practical to cover all the space on the pitch. As a basic rule of thumb your team is compact on defense and expanded when you have the ball. Being compact in the space between you and your teammates allows the formation to hold more firm which provides cover to the immediate player pressuring the ball and allows the other defensive players to cut off as many passing lanes as possible to other opposing players. Expanding when your team has the ball allows more space for the player on the ball and more open space for players off the ball to move into space and open up passing lanes/make runs. Tight Man to man defense would drag defensive players out of position/formation leaving large gaps or open spaces on the field for the opposing team to exploit. You do see more tight man to man marking on corners and set pieces as the immediate threat is the ball being whipped into the box in which case the amount of space to defend is much smaller, like in basketball.