Al Horford signed an extension with the Celtics. What does that mean? 

Celtics

With Horford, the Celtics have a chance to keep their core together for the foreseeable future.

Al Horford knows his NBA career is winding down.

Earlier this season, the Celtics big man told Heavy.com’s Steve Bulpett he wants to play for “two, three more years for sure.” He also was direct when Bulpett asked if he wants to finish his career in Boston, answering in the affirmative.

“My biggest thing is just enjoying this opportunity and this moment,” Horford said. “It’s not often that you’re part of a team and you love what you have going on here, but also having a real chance. That’s something that’s special.”

On Thursday, Horford moved a little closer to finishing his career in Boston, signing a two-year extension with the Celtics reportedly worth $20 million. The deal puts him under contract through 2024-25 and — if it proves to be his final NBA contract — will leave him with more than $285 million in career earnings.

“Al is such an important part of our team,” Celtics president of basketball operations Brad Stevens wrote in a statement. “He’s a high-level player who enhances everyone around him on both ends of the court. His work ethic, commitment to his body and craft, and his unselfishness set a daily example on how to win big in the NBA. His leadership has had a big impact on the coaches and players he’s competed alongside here in Boston, and we’re excited that he and his family are choosing to remain Celtics for years to come.”

So why is Horford such an important piece for the Celtics? Here’s a closer look.

Horford is still highly productive

According to Horford (speaking to Heavy.com), Danny Ainge once told him he could play until 40 given how well he takes care of himself.

That, clearly, was a prescient statement by Ainge. On the court, the 36-year-old Horford — who made just 21 3-pointers in his first eight seasons combined — has reimagined himself largely as a stretch big. As part of a dizzying Celtics offense, he’s shot 48.8 percent from 3-point range so far. Per Synergy Sports, spot-up opportunities make up the bulk of his offense — a change from his time in Philadelphia, where the 76ers used him most frequently in the post.

The result is that Horford is unbelievably productive. In spot-up opportunities, he’s averaging 1.44 points per possession (PPP) with a wild 72.3 percent effective field-goal percentage. He’s also posting 1.46 PPP in transition. Horford’s usage has never been lower (11.6 percent), but his efficiency is through the roof and he’s a crucial cog in the Celtics’ ball-movement happy offense — his assist rate adjusted for his usage is in the 90th percentile league-wide, per Cleaning the Glass.

Horford has started all 18 games he has played so far this season, which makes sense on multiple levels. The Celtics’ starting lineup with Horford and Derrick White has trounced opponents, and last year’s starting lineup — which featured Robert Williams instead of White — was the best starting lineup in the league. His low-usage offense, meanwhile, makes him a perfect fit alongside ball-dominant players like Jayson Tatum, Jaylen Brown, and Marcus Smart.

But Horford could also easily transition to the bench over the next two years, if the Celtics want to limit his minutes to keep him available for the postseason. His versatility on both ends is a major selling point.

Horford gives key rivals fits

Defensively, Horford is nearly invaluable for the Celtics because of the specific problems he presents for key rivals.

Horford is probably best known for being one of the best defenders in the NBA against 76ers star Joel Embiid — so much so, that the Sixers signed Horford in an ill-fated pairing following the Celtics’ disastrous 2018-19 campaign. Reunited with the Celtics last season, Horford spent 68.7 partial possessions guarding Embiid, and the Sixers star shot just 31.3 percent from the floor (in their lone matchup this season, Embiid shot 5-for-10 against Horford).

Meanwhile, in the postseason, Horford guarded Bucks star Giannis Antetokounmpo for 180.1 partial possessions. Antetokounmpo managed to shoot just 36.3 from the floor in the postseason, which was one of the key reasons the Celtics advanced to the Eastern Conference Finals.

Horford doesn’t use explosive athleticism to guard Embiid or Antetokounmpo, just great positioning and old-man strength. Whether he can keep taking the battering-ram damage Embiid and Antetokounmpo inflict as he ages remains to be seen, but the possibility of limiting both stars over the next three postseasons is well worth $10 million per year.

Horford’s new deal opens up space going forward

Horford would have been an unrestricted free agent after this season. While he expressed interest in remaining with the Celtics, nothing is guaranteed in contract negotiations.

By signing this deal, Horford locked in guaranteed money for himself. He also did the Celtics a favor — the non-taxpayer mid-level exception was expected to be nearly $11 million next season, and the Celtics (who will pay the luxury tax for some time) would not have had access to it. The Celtics can now improve their roster via the smaller taxpayer MLE, and they can work to negotiate a new deal with Grant Williams to keep their roster together.

As noted by MassLive’s Brian Robb, nine of the players currently in the Celtics’ rotation — including Payton Pritchard and Luke Kornet — are under contract for next season, in addition to the injured Robert Williams and Danilo Gallinari. The only player not under contract next season is Grant Williams, who will be a restricted free agent (meaning the Celtics can match any offer sheet a rival throws at him). In other words, if this season continues to be this successful, the Celtics will control their own destiny to bring everyone back next year … with the added benefit of the taxpayer MLE.

Conclusion

Horford is still a highly productive player for this team, and betting on his longevity is a solid wager, especially given the relatively low price of his services and his enthusiasm for remaining in Boston.

The Celtics and Horford made the mistake of splitting up once before. A shrewd move by Brad Stevens in his first summer as President of Basketball Operations brought them back together. Now, it appears likely the two sides will remain in partnership for the rest of Horford’s career.