Transition defence is a rebounding trade wearing a disguise

Every gain in getting back is paid for on the offensive glass, and most teams never write down the exchange rate.

You can improve your transition defence tomorrow. Send everyone back. Nobody crashes, ever. Your opponent's fast break points will fall off a cliff and your assistant coaches will look brilliant.

You will also give away a large share of your second chance opportunities, and second chances are among the most efficient possessions in the sport, because they start with the defence scrambled and the shooter already inside the arc.

So it is a trade, and I keep finding that teams evaluate the two halves separately. Offensive rebound rate lives on one page. Transition defence lives on another, usually with a different assistant responsible for it. Nobody writes the exchange rate down. What does one extra crasher buy in offensive rebound percentage, and what does it cost in points allowed per opponent transition possession?

The rough shape of the answer is knowable from a team's own tracking data. A fourth man on the glass adds a few percentage points of offensive rebounding. It also converts a share of misses into opponent possessions that begin with a numbers advantage, and those possessions are worth meaningfully more than an average half court trip. Multiply through and the trade is close, which is exactly why it should be made deliberately rather than by habit.

The answer is also not the same for every team. If your bigs are strong offensive rebounders and your opponent's guards do not push, crash. If your centre is poor in traffic and the other team has a point guard who looks up the floor before he even has the ball, do not. The default should be situational and it should change during a game, not just between seasons.

What annoys me is the moralising. Crashing the glass gets described as toughness and getting back gets described as discipline, as though the two were virtues rather than options with prices. They are options with prices. A coach who insists his team must do both is really saying he has not decided.

Write the number on the whiteboard. One extra crasher costs this much and returns this much. Then let the players see the arithmetic, because a player who understands the trade makes the right read at the release, which is the only moment the decision is actually available.