On the Warriors falling into the trap of not trapping the box against the Lakers

Forgetting a key defensive principle costs the Warriors on Christmas.

At the 10-minute mark of the fourth quarter, Brandin Podziemski found himself switched onto LeBron James after the Los Angeles Lakers ran one of their pet half-court sets (“Horns Chin”). Podziemski’s switch was prompted by the “chin” cut performed by his man (Gabe Vincent) off of James’ screen at the elbow. Draymond Green — James’ man — instructs Podziemski to switch onto James.

Seeing he has a much smaller man in front of him, James prepares to isolate against Podziemski for a potential drive to the rim. While this isn’t a matchup the Warriors would prefer for Podziemski, take note of his positioning, as well as Green’s — the low man from the weak side whose responsibility is to be the first line of help should James decide to power his way to the bucket:

A core philosophy of the Golden State Warriors’ defense is the “no-middle” approach — that is, prevent opponents from driving down the middle of the lane as much as possible. As such, Podziemski positions himself to James’ right in an attempt to “weak” him toward his left (“weaking” therefore is a coverage where a defender shades a ball handler toward his weak hand). Green is in position to rotate on James’ potential drive, something the Warriors call “trapping the box.” Meanwhile, it is Steph Curry’s responsibility to sink back and take Green’s man if and when Green steps up to rotate on the drive. Gary Payton II’s responsibility is to zone up between the corner and the wing and virtually defend two players simultaneously:

As expected, James powers through Podziemski, and while that isn’t ideal, Podziemski is comforted by the fact that Green — one of NBA history’s all-time help defenders — is behind him, ready to step up and relieve him of having to stop an all-time rim attacker by his lonesome. In that regard, Green is successful; he stops James in his tracks and forces a miss:

Green “trapping the box” in this instance has been a core tenet of the Warriors’ defense under Steve Kerr — from the days of Mike Brown as their defensive coordinator in 2022, to Kenny Atkinson taking over that mantle, and now with Jerry Stackhouse as their main defensive coach. Players have been lauded for performing it and admonished for forgetting it — the former happened in Moses Moody’s case during his rookie season, in which an article by The Athletic’s Anthony Slater mentioned Moody being praised for his help defense in such situations.

“Trapping the box” is one of several principles the Warriors have in their arsenal that has helped them stay within the top 10 in defensive rating (eighth in non-garbage time prior to the Lakers game, per Cleaning The Glass). Defense hasn’t been a general problem for them — it’s been on the offensive end where massive slippage has occurred, in the form of a classical problem they have had since time immemorial: the non-Curry minutes.

Per the NBA’s own on-off data, the Warriors have scored 118.7 points per 100 possessions in the 748 minutes of Curry on the floor; that number drops all the way to a ghastly 100.9 points per 100 possessions in the 649 minutes of him off the floor — a drop off from what would be considered the fourth-best offense to easily the worst. That problem plagued them for most of their game against the Lakers, until Curry stepped up to rescue them via a couple of timely three-point shots in clutch period and finishing with 38 points on 6-of-9 shooting on twos, 8-of-15 shooting on threes, and 76.4% True Shooting, breaking a career-long streak of mediocre Christmas Day performances.

His second three — born out of a well-drawn after-timeout set — gave the Warriors a chance to send the game into overtime, provided they were able to get a stop in the ensuing possession:

That ensuing possession involved another isolation situation — with Austin Reaves having the whole left side of the floor to himself against Andrew Wiggins, who had Green to his immediate left guarding James. Curry was on the weak-side wing keeping tabs on Max Christie, Dennis Schröder on the weak-side corner guarding Vincent, and Jonathan Kuminga sticking close to Rui Hachimura.

When an isolation like this occurs, it *should* trigger the Warriors’ trap-the-box principles — but a problem in terms of positioning occurs:

A valid argument could be made that Wiggins shouldn’t have been blown by so easily against Reaves. Weirdly enough, Wiggins has Reaves to thank for choosing to drive to his left instead of the right and down the middle where the Warriors don’t want the ball to be at in accordance with their no-middle philosophy. As such, Wiggins still has help behind him in the form of the baseline (considered an additional inanimate defender in this instance) and Kuminga, the first line of help defense whose role is to trap the box. If Kuminga makes this rotation, it forces Reaves to have to make a tough shot against two pairs of long arms, or skip the ball toward the weak side, which gives the others enough time to rotate and force a contested long jumper.

But as can be seen in the image above, once Reaves makes his move, Kuminga is inexplicably face-guarding Hachimura — who is out of bounds and not within the active playing area. Wiggins is caught having to funnel Reaves toward a non-existent help defender — non-existent due to Kuminga’s lack of situational awareness.

If their trap-the-box principles were followed, this is what the rotations should’ve looked like:

Alas, with Kuminga late to diagnose the situation and, therefore, unable to do anything to help on the drive, Reaves manages to slither past Wiggins and score the winning bucket — one that sent the Warriors to their 11th loss in 14 games, forcing them to ask questions of themselves and find answers to a season that is quickly running out of them.