The value of each player's awareness of the importance of team defense cannot be overestimated. The quick transitions between offense and defense in basketball sometimes obscure the value of concentrated defensive effort. Scoring occurs rapidly and more easily than ion other sports. Because of this, players are more susceptible to believing that a letdown on defense can always be quickly compensated for on the subsequent possession. Perhaps it's more convenient in basketball to rationalize inadequate defense with the old cliché about the best defense being a strong offense. Unfortunately, the offense oriented statistics we have made popular in our sport do little to offset this accent.
Human nature, in general, is such that we instinctively feel more aggressive and exuberant when we take the offensive, as opposed to finding ourselves on the defensive. At North Carolina, we have tried to alter that accustomed role. We believe in taking the offensive on defense.
We attempt to instill team pride in defense. A team effort must be required in order to get the job done. The pressing, pressure defense which is our primary attack requires five defensive players working together against four offensive men. We are usually off someone, overplaying, always helping, and always looking for help. Of course, we do assign individual match-ups prior to a game. However, we seldom tell a player that he has the sole responsibility of keeping his man down. His job is to contribute his efforts in an overall manner that will help our team keep our opponent down.
From "Basketball Multiple Offense and Defense" by Dean Smith