Why the Celtics’ interior defense is better than advertised

From the start, Boston’s interior defense looked doomed. The Celtics loaded up on centers to start their season in hopes of one or two sticking as solid rotation players. Daniel Theis, now in his third year with the team, has unsurprisingly emerged as one of them. Enes Kanter, to injury or otherwise, hasn’t impressed in the early going. Robert Williams has been a plus, but is still slow to move his feet and establish himself as a solid pick and roll defender. Vincent Poirier hasn’t seen the floor much. Tacko Fall is now in Maine on a two-way deal.

The Celtics haven’t found many answers from their selection of centers, but from somewhere else instead.

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First, the 6’4” Marcus Smart. I was foolish enough to tweet (and then use that tweet in an article on here) that I didn’t think Smart should play extended minutes at center or forward, saying that his defense on Giannis in the FIBA tournament was enabling the opinions of all the wrong people. This is all too common for me - to look at something so plain and simple - and interpret it as either luck, an outlier, an unrealistic expectation, or all of the above because it doesn’t align with my idea of how things work. Since then, Marcus has been a staple to Boston’s early defensive identity in the paint, not where we’re used to seeing him.

In Boston’s last stand in their season opener against the Philadelphia 76ers, he was assigned to defend Al Horford for a fourth quarter stretch. This ultimately led to nothing, but had me wondering if that would be his role in Boston’s closing lineup. In the second-half evisceration of the Milwaukee Bucks, Smart terrorized Giannis in the fourth quarter. Per NBA Stats, Smart guarded Giannis for 4:26, the second most time he’d spent defending any one player in any of Boston’s first six games.

When the Celtics narrowly beat the Knicks at home, Smart defended Julius Randle on occasion, prompting Brian Scalabrine to clarify more than once: “Remember, this is not a mismatch.” And most recently, Smart closed out Cleveland by matching up with Kevin Love.

Smart covered Love for 8:26 in yet another close victory, by far the most time he’s spent on any individual match up in six games.

A defense-first point guard blossoming into a stretch “six” is simply too much for me to process. I’ve never seen player development take this path before, which is probably why I wrote him off as a permanent fixture in the front court.

It may be unconventional, but it allows Boston to to something that they’ve had trouble with in the past: playing their best five players to close a game without having to question who those players are and how they fit together. If Smart wasn’t a capable center, the Celtics might still be searching for answers.

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The other diamond in the rough has been the bonus of Grant Williams’ readiness as a rookie. True to the ‘winning plays’ brand of basketball he plays, a lot of Grant’s production doesn’t show up in the box score. As one of the stabilizing forces in two scrappy games against the Knicks, he was credited for only five rebounds in almost 46 minutes.

Thirty percent of shot attempts against Williams have been within six feet of the basket, in which opponents are shooting 44.4%. The only Celtic with a better mark is Semi Ojeleye at 41.7% on similar frequency. Smart is holding opponents to 50% shooting from short range.

In contrast, 50% of all shots against Robert Williams have come within six feet - opponents are shooting 68.8%. Daniel Theis’ numbers are almost identical. It’s a curious outcome based on traditional thinking: tall players should defend tall players.

Normally, I’d tell you not to read too much into a small sample size. I think I’ve changed my mind on this, to an extent. If a team shows who they are and how they play, it’s pretty safe assume your eyes aren’t lying to you. From Day One, this team has shown a willingness to play together, play hard, and play smart. They’re not due for any major regression because, by the numbers, they haven’t blown anyone away.

The Celtics might not win five out of every six games. But, they can play the same way for all 82. Marcus Smart is the anchor. May Grant Williams follow the same path. Both Smart and Williams are trusted to take tough assignments in the front court, and the Celtics have benefited from it. Boston’s defense still has some holes, but what they currently have is sustainable.