Blocks are the worst way to judge a rim protector

The best interior defenders spend their careers preventing shots that never get attempted or counted.

A block is a highlight. It is also, quite often, evidence that a defender let somebody get all the way to the rim.

The shots that never happen are the ones that matter. An offensive player drives, sees the help arriving, and pulls the ball back out to reset. Nothing is recorded. No block, no contest, no defensive rebound, and yet the defence has just converted a rim attempt into a perimeter possession with a shortened clock, which is one of the more valuable things a defender can do in an evening. The player responsible finishes the night with a stat line that looks quiet.

Field goal percentage allowed at the rim is a better instrument and it has its own hole in the middle. It only counts the attempts that occurred, so a defender who deters heavily faces fewer and often harder attempts, while one who deters nothing faces a stream of easy ones and can post a similar number by simply being present for a lot of layups. Volume and rate need reading together and usually are not.

Then there is the part that gets ignored altogether, which is what the defender's positioning does to his teammates. A centre who can be trusted to cover the rim lets the perimeter defenders play higher, closer to shooters, more aggressively over screens. That aggression shows up in the perimeter players' numbers. It was purchased by the man behind them.

This is why on and off defensive ratings, for all their noise, tend to be more revealing for bigs than individual counting stats. The effect is systemic and the counting stats are individual.

There is a version of the opposite error too, which I have seen in scouting conversations. A big who blocks a lot of shots while gambling out of position, leaving the defensive glass, giving up second chances that nobody attributes to him because the rebound goes in the column of whoever failed to grab it.

Watch a possession and ask what the driver decided. If he did not go, somebody made him not go.

That decision, made forty times a night by opponents who never appear in the box score, is what rim protection actually is.