Celtics’ second quarter in San Antonio is a microcosm of defensive struggles

The Celtics defense (or lack there of) has been talked about a lot this season. It is just not at the level it usually is under Brad Stevens and there have been several red flags in their losses.

Consider the second quarter against the San Antonio Spurs on Wednesday night. The Spurs outscored the Celtics 36-17 in a downright embarrassing quarter for the team. The offense went cold, but it was more about the continuous loss of defensive effort that has plagued this team all year.

The biggest difference this season from last season’s defense that ranked 4th in the league is the lack of consistency. Wednesday night was a good example of the energy being raised by the other team, but the Celtics just stayed content and stagnant as a run was happening.

Specifically, it was Keldon Johnson and Lonnie Walker IV who gave a spark to the Spurs team combing for 20 points in that quarter. The following clips illustrate the breakdown of the Celtics defense.

This first one exposes Jaylen Brown getting lost on the floor and letting Keldon Johnson have an easy back door cut to the rim. Jaylen is obviously known for good defense but gets caught ball watching as DeMar DeRozan finds the cutting Johnson. It is only one possession, but it does feed the season narrative of lazy defense turning into easy baskets.

Here, the effort is not much better from Brown, Robert Williams and Kemba Walker as they get bullied down low by 6’5” Keldon Johnson for his fourth basket in a row at that point. There should never be instances where one player gets an offensive rebound over three defensive players who have already established themselves in the paint. To add insult to injury, Johnson then got the shot off for a put-back basket.

The effort is one (huge) thing, but the Celtics also made schematic changes to address their porous defense. Stevens even went to a zone later in the game because nothing was stopping the Spurs.

Daniel Theis has made major strides this season despite playing out of position and losing his spot in the starting lineup. He’s been better on the offensive end, but his defensive awareness playing the 4 is a work in progress.

LaMarcus Aldridge had his way with Theis with most of this game scoring 8 points in that quarter all with Theis defending him. This clip is one of the baskets where Theis gets confused and is caught out of position. He gets suckered down on the Patty Mills drive which leaves Aldridge on the perimeter for an open look three-point bucket.

It was not only Theis struggling in that quarter as the Spurs shot 4-for-7 from beyond the arc. A major problem was the late and occasionally incorrect switching that led to open shooters. Some instances were effort and hustle-based and others were just out of position. Stevens switched to that zone shortly after half, and the switching around the arc seemed to be a major reason. This clip says it all. (What are you doing, Javonte!?)

All in all, the Celtics did turn it up in the second half on the defensive end. Unfortunately, it proved too late to flip the switch. Stevens will go over film with them and will grow and learn from this. They know they have the talent on that side of the ball to control the pace of the game. It is just channeling the intensity for a full 48 minutes.