Every blitz is a rebound you agreed to give up

Trapping the ball handler wins possessions and quietly hands back a share of them on the offensive glass, which nobody puts in the same column.

Send two at the ball and you have four defenders covering five men behind it. Everyone accepts that trade in principle. What gets skipped is the second half of the bill, which arrives when the shot goes up and your defense is in a rotation rather than in box out positions.

The mechanics are simple enough. A blitz forces the big man out to the arc and the low man up to the roller, so at the moment of the shot your two best rebounders are standing outside the area they need to occupy. The wing who rotated down is now expected to box out a centre. He will not. He was not built for it and he arrived facing the wrong way.

So the honest accounting for an aggressive coverage is not the turnover rate it generates against the points it concedes. It is that, plus the second-chance points it hands over, and I suspect that third term is large enough to flip the verdict on some of the schemes we describe as high variance. High variance is often just an unmeasured cost showing up unevenly.

There is a defensible version of blitzing that accounts for this. Blitz early in the clock, where a turnover is worth the most and where a miss is likelier to be a long one that comes off to the perimeter. Do not blitz late, when the offense will take a contested shot anyway and the only thing your rotation adds is a free run at the glass.

The other thing I would say is that opponents know. Teams with two committed offensive rebounders deliberately invite a trap, because they are not trying to beat the trap, they are trying to get the defense scrambling before a shot goes up.

There is a version of the argument that goes further and I have some sympathy with it. If your defense is going to concede second chances anyway, you may as well take the aggressive coverage that generates turnovers, since the glass is lost either way and turnovers are the only currency that produces easy points at the other end. That reasoning holds for teams with no rim protection. It does not hold for anyone else.

You do not really give up two on the ball. You give up the glass, and you find out about it later.