How the Celtics got their groove back: a look at Al Horford’s varied offensive gravity

Al Horford’s long-range shooting was a revelation last year. The Boston Celtics’ big man drained 42.9 percent of his 3.1 attempts per game from beyond the arc a season ago, a mark that was good for 10th in the league overall and first among players that regularly filled minutes at the center position.

Horford’s competence from deep was a boon to Boston’s offense. It breathed spacing into driving and passing lanes, and served as a balm for the Celtics’ lack of elite shot creation and scoring options in the wake of injuries to Kyrie Irving and Gordon Hayward. Defending Horford in the pick-and-pop is a nightmare of difficult decisions.

Stay attached to him closely, and you risk exposing an easy path to the rim for the play’s primary operator. Commit to the ball for a fraction of a second too long, and Horford will launch from deep and crush you under the weight of basketball math’s greatest truth: 3 > 2.

Even when defenders play with perfect timing, Horford is crafty enough to turn a simple pump fake into access to the paint, where he’s an excellent decision maker and a threat as a driver, passer, and shooter.

That makes him an exceptionally valuable offensive weapon, even if his modest scoring average suggests otherwise. Horford is the tide that raises all ships. His gravity, passing, and selflessness generate oodles of open looks and create all sorts of seams for his teammates to attack, but it’s all contingent upon him being a willing, elite-level shooter. The threat of Horford firing from three is far more impactful when he’s hitting like Dirk Nowitzki and not Paul Millsap. He hasn’t been doing that for the majority of the 2018-19 season.

Horford has made 34.1 percent of his shots from beyond the arc, a respectable albeit uninspiring rate. The Celtics have struggled because of it. Their offensive rating with Horford on the court sits at just 105.9, roughly equivalent to a bottom-five level of efficiency. Things have been shifting recently, however.

Boston finds itself in the middle of a four-game winning streak, during which it’s scored 124.5 points per 100 possession. Horford’s three-point percentage during that run of scorched earth offensive dominance stands at 50.0 percent. The simple takeaway here is that the Celtics play better when one of the most important components of their offense is functioning at its optimal level. Boston not only benefits from the points that Horford’s three-point makes generates, but all of the ancillary impacts highlighted above.

Toss in the added defensive bonus of opponents having fewer opportunities to get out in transition, and the analysis seems plenty clear, but there is even more nuance to be explored here. Horford has actually been shooting the ball less from beyond the arc during Boston’s recent streak of success, hoisting just 2.7 attempts from deep, as compared to 3.7 for the full year.

The Celtics have begun featuring Horford more frequently as a roll man. He’s not the kind of athlete that can totally collapse a defense in such instances, but he’s a capable finisher near the hoop and a canny passer. Defenses need to account for him if he’s headed to the bucket.

His gravity as a roller is sufficient to force rotations that lead to miscues that Boston can attack later in the possession.

The Celtics have struggled dearly to get looks at the rim this year, a reality driven, to a degree, by the fact that opponents don’t expect their actions to put much pressure in that direction. Boston’s offense has long emphasized getting the ball to talented isolationists and hunting out open threes, both of which are valuable, but neither of which require opponents to think much about protecting the paint. Sending Horford in that direction more often changes the calculus of the shot selection and the geometry of the floor.

His ability to manipulate defenses as a roller is different from the influence he has on opponents as a three-point shooter, but they’re branches of the same tree. The more Boston can integrate both into its offense the better off they’ll be. Defending Horford as a screener with a strong inclination that he’ll pop is difficult enough. If rolling is an option too, then the number of spaces on the floor that must be accounted for increases and the complexity of associated decisions does as well.

And that is the crux of what makes an offensive philosophy sound. The more painful choices opponents need to make, the better.

Let’s take a moment to temper expectations. The Celtics run of recent success hasn’t come against the stiffest competition. It’s not all that hard to look like a skilled roll man against the likes of Enes Kanter. Asking Horford to fill such a dynamic function as a dual threat of a screener isn’t a small request for the team’s elder statesman. Boston needs to be careful about the workload they ask him to take on during the regular season.

The Celtics have enough talent not to require Horford to be the most effective version of himself as an offensive hub each night though. What matters here is that Boston has discovered something to, at worst, keep in its back pocket for more meaningful games, and at best, evolve its offense with. There is a real structural advantage to broadening the threat of what Horford might do after setting a screen that exists regardless of competitive context.

Discovering it has born some serious fruit in the short-term. Even if the Celtics’ offense regresses to the mean moving forward (and it will), having done so will be of great utility in the long run.