Al Horford’s March Madness – CelticsBlog

In June, during the next NBA Finals, Al Horford will turn 39 years old. Earlier this season, there were some doubts about his ability to keep performing with another long season ahead, and Kristaps Porzingis sidelined for the first few months. However, when March was around the corner, Al Horford buried those doubts.

While Kristaps Porzingis was dealing with a mysterious illness, Al Horford started the month with a defensive masterpiece against the Denver Nuggets and kept performing through March’s 10 games. Before deep-diving into the film, let’s have a look at Al Horford’s season averages vs. his stats in March.

As his minutes increased from 27 to 32 in March, all the statistical indicators also went up significantly. His usage rate (a measure of offensive load) went from 13.5% to 17%, showing that the Boston Celtics coaching staff gave him more responsibilities on offense. While his load increased, so did his efficiency — from slightly above average (56.2% true shooting) to an elite mark (61.3%) — and this is not because of shooting luck.

His three-point percentage remained the same, but the Celtics decided to get Al Horford closer to the rim, into the paint. In March, he more than doubled his number of free-throw attempts per game and went from 29% of his points in the paint to 35%. The rebounding volume also shows that Al Horford was asked to be more aggressive inside — and it worked!

One last statistical argument that leads us to think the Celtics have involved Al Horford a lot more during this recent stretch is his number of assists in March: 3.5 — more than he has ever averaged since being traded from OKC back to Boston. Nonetheless, numbers are interesting, but how does it translate on the court? What did the Celtics coaching staff design to involve Al Horford offensively? And also, what changed defensively?

Empty side pick-and-roll

These actions were very important for the Boston Celtics’ success last season. This is a great way to shamble the defensive organization, no matter the defensive coverage. Often, the defense may try to switch and therefore avoid giving the Celtics a gap. But by switching, they are giving the Celtics a mismatch. Let’s look at these two actions against the Denver Nuggets, early in March.

It may seem very basic, but it opens up so many great things for the Celtics. Let’s look at the setup first. Payton Pritchard and Al Horford are playing a pick-and-roll next to an empty corner (that’s why it’s called an empty side action). Because of that, nobody can come from the strong side to help. At the top, you have Jayson Tatum. His gravity makes it impossible for Christian Braun to come and stunt if Pritchard goes left.

On the other side, Luke Kornet is in the slot. Joe Mazzulla has made a habit of positioning him there to maximize his connector skills and drag away the opposing center. Then, you have Sam Hauser in the corner — and all that takes away the weak side’s help. Because of the court mapping, if the Denver Nuggets switch, they are leaving a mismatch with no help. If they decide to stay with their man, nobody can cover the roll or help on Pritchard’s potential drive or pull-up. They were doomed before it started.

As Al Horford gets his matchup and bullies Jamal Murray toward the paint, Kornet slides down to the dunker spot. At first, you might think that would be a problem because it could take away spacing. However, he places himself deep enough under the rim, on the other side of the paint, that Nikola Jokic cannot leave him alone. Despite being in the paint, the Joker must leave his teammates alone against a taller and stronger player in the post.

On the very next possession, the Celtics ran the same play. This time, Kornet stays up, but Jokic goes to help in the paint anyway. Pritchard swung the ball to the Celtics’ center, who got into a handoff action with Hauser. This simple move drags Jokic out of the paint, and Horford is again all alone against Murray in the paint, able to finish at the rim.

Another example below with different players but the same court mapping. See how Kornet moves up while Horford runs to set a screen for Jaylen Brown. As the screen happens, Horford finds a way to put his matchup on his back, giving him free access to the rim, and Brown can find him with a single pass. Once again, they use Kornet to connect, and Horford is free at the rim thanks to an empty side pick-and-roll.

That isn’t just a glitch or a random event — the Celtics literally spammed this action against the Lakers to start the third quarter. The goal was to force LeBron James to switch and be far from the paint, while Al Horford could easily attack Austin Reaves. With that offensive approach, the Celtics created a big enough gap to win against the Lakers in March and ended their home winning streak in the most anticipated game of the season.

What feels different compared to earlier this season is that Al Horford now has plays designed for him to attack mismatches. This explains why his number of free throws, his efficiency, and his percentage of points in the paint are all rising this month. We also see him being more aggressive after a closeout, driving to the paint instead of passing the ball. In this example against LeBron James, it’s clear that Horford is more aggressive than he ever was this season.

Yet another notable change in March is harder to capture with stats because it’s on defense. Since tracking data on defensive coverages is hard (impossible?) to get, I don’t have the proper numbers to validate my hypothesis. Nevertheless, there is something different about Al Horford’s defense.

Switch-Al is back

Earlier this season, in some of the 10 takeaways I wrote, the Celtics coaching staff’s tendency to ask Al Horford to drop didn’t make sense to me. The big man isn’t the best at protecting the rim in drop coverage. The way he positions his hips and feet isn’t always accurate, and he isn’t a seven-footer who can compensate for those slight errors with size at the rim.

However, Al Horford always has been — and remains — a beast when he is asked to switch. And that’s exactly what the Celtics asked him to do over the last few weeks. While I couldn’t access the tracking data regarding pick-and-roll coverage for Al Horford, there is a statistical indicator that leads me to think it is working well.

Opponents’ rim frequency has dropped from 29% to 25% in March, and there’s a fair chance that’s due to the switching defense. And Al Horford didn’t switch on just any players in March. As the Celtics played against OKC, the Nuggets, the Lakers, and other competitive teams, Al Horford had to switch on some of the best players in the league.

His three defensive masterpieces came against the three teams mentioned above, where he was able to switch onto former MVPs like Nikola Jokic and LeBron. His ability to switch 1 through 5 on sequences makes him a very important alternative to Kristaps Porzingis’ deep drop approach. Because Horford can switch like that, the Celtics can deploy a defensive army with Derrick White, Jrue Holiday, Jaylen Brown, Jayson Tatum — and now Horford — where no one is a natural mismatch.

With the recent offensive adjustments and the accurate defensive approach, the Boston Celtics can be confident they have one of the best defensive bigs in the league — with an efficient and versatile offensive game — ready to help the Celtics win a back-to-back, like he did with the Florida Gators in 2007.