In a Zone defense, each of player is responsible for guarding a specific are
of the court (their zone). The numbers refer to the spacing of defensive
players, e.g. in a 2-3 zone there are 2 defenders guarding the perimeter and
3 players guarding inside.
A zone defense can be effective at taking away penetration, keeping players
out of foul trouble and hiding a bad defender. Additionally, you don't have
to be deep to play a zone - since the players are only working when the ball
is in their zone, they don't need the stamina needed to play man to man or press.
A Zone defense allows many wide open outside shots and can give up a lot of