Deep Dives Continued: More on the Postscript to a Shot Block

A quick follow up to yesterday’s deep dive into shot blocking and it’s aftermath, Nate Duncan and others were wondering just how do offensive and defensive rebounds compare with balls knocked out of bounds from shot blocks. So in the interests of extreme nerdery, I decided to look. Again, the 4 main outcomes of a blocked shot are an offensive rebound, a defensive rebound, a team offensive rebound or a team defensive rebound. Ignoring the pie-chart haters, here’s how those outcomes break down for a blocked shot at the rim as opposed to regular old misses:

When the ball stays in play, the defense rebounds slightly more frequently from a block than from a miss, but overall, the offense recovers slightly more blocks because of all those pesky swats out of bounds. But what happens next? Nate posited that offensive rebounds, both in bounds and team, might be negatively impacted by the shot clock not re-setting on most blocks, as the ball never hits the room. And he’s right!

First, let’s compare ensuing possessions on offensive team rebounds. On run of the mill out of bounds plays, the offensive team had an eFG% of 47.9%, slightly better than the “normal” average on post-deadball scenarios. Without losing my mind trying to parse everything out, I’d suggest this slight uptick in efficiency is from the benefits of BLOBs and SLOBs[1. Baseline and sideline out-of-bounds plays. However, comparing to a play after a blocked shot, and offensive efficiency plummets, as teams shot a collective 38.4% on BLOB/SLOB situations following a block. It’s a pretty small sample size, but the fact that teams were working with a short shot clock[3. The average block at the rim came with around 13 seconds remaining on the shot clock.]

By comparison, when there was an individual offensive rebound, that is one a carom which stayed in bounds, from a missed shot near the rim, shooting efficiency after shot blocks was about the same as following regular misses. On putbacks[4. Not just putbacks, as the ball could easily have been reset and re-circulated, but “shots after offensive rebounds from regular old misses that weren’t blocked” isn’t the most concise bit of verbiage, so “putbacks” it is.], the defense fared slightly better after blocks than not, with eFG% of 57.1% and 56.1% respectively. However, overall efficiency was just over 5 points per/100 lower after shot blocks. This was largely due to turnovers, as teams turned the ball over nearly twice as often after blocks as after non-blocked misses. In particular, they suffered deadball turnovers – a category which includes 24-second violations – 225% as often. All-in-all teams had an estimated points per play[7. I substituted league average for foul shots accruing in these scenarios both for ease of calculation and because it’s a bit off to assign credit or blame what would likely be random variation across relatively small samples of free throw attempts to the preceding action. I’ve called these measures aPPP and aTS% for “assumed” points per play and true shooting percentage.] of 1.07 following blocks and 1.12 otherwise.

See below for a summary of how play proceeds in various scenarios:

So in summation, blocking the ball out of bounds? Not that bad. Except for one thing. If you keep the ball in bounds AND a teammate recovers, good things happen. When I looked at the kinds of misses which tended to lead to fast breaks the other way misses at the rim, and especially blocked misses at the rim where high on the list. Unsurprisingly, this shows up in numbers. Teams did get out on the break more after rebounding blocks at the rim, shooting 55.7% eFG and 57.7% aTS% in those situations as compared to 52% eFG% and 54.4% aTS% on regular old misses. A rebounded block isn’t quite the offensive catalyst going to other way as would be a steal, but it’s not far off. So, while swatting a shot out of bounds isn’t the end of the world, it can hurt if mostly by eliminating a high quality opportunity the other way