Is the Boston Celtics preseason defense for real?

The Boston Celtics are prime candidates to take a big step back on the defensive end of the court this year. They lost a pair of exceptionally talented anchors over the summer in Al Horford and Aron Baynes, two ultra intelligent, mobile bigs with impeccable ability to guard multiple players at once.

The Celtics surrendered 109.2 points per 100 possessions when their two departed big men were not on the court last year, compared to 107.5 with just Horford playing, 105.3 with just Baynes, and an uber stingy 100.0 in shared time. Boston replaced its duo of defensive studs with a comparatively uninspiring group of Daniel Theis, Enes Kanter, Robert Williams and Vincent Poirier.

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Theis has the knowledge and timing to defend well, but lacks the athleticism and girth needed to bang with league’s biggest bodies. Kanter is a known liability. Williams and Poirier have intriguing athleticism and movement skills, but both are young and have done little to prove they’re ready to play a central role at the NBA level.

All signs point to defensive slippage, with the exception of one fairly notable marker: the Celtics preseason performance. Boston posted an absurd 84.7 defensive rating across its four preseason games.

The Celtics have directed their cadre of long athletic wings to pressure up on ball handlers, stick their mitts into passing lanes, and generally wreak havoc all over the court, trusting one another to be in the right place at the right time.

The plan has worked beautifully, as Boston walked its way to an undefeated preseason, largely as a result of the headaches it was able to create on the defensive end. The Celtics defensive performance was as encouraging as could possibly be imagined. Enough so to make one wonder if perhaps prognostications of Boston’s defensive demise were ill-advised.

Expectations should be tempered in that regard. The Celtics played precisely zero dynamic creators off the bounce in the preseason, and even fewer threats to make impressive passes after accessing the paint. It’s not hard to imagine Boston’s intense ball pressure turning into easy blow bys and defensive breakdowns against players who aren’t Terry Rozier, Collin Sexton, and D.J. Augustin.

It’s also not unreasonable to think that the Celtics bigs may have more trouble when they face off against more skilled, higher caliber athletes. Daniel Theis was at the heart of Boston’s most impressive defensive units, but he was only required to slow down the likes of Tyler Zeller, Mo Bamba, and Jarell Martin. The Celtics will be in trouble when Joel Embiid, Giannis Antetokounmpo, and similar athletic marvels come to town.

Boston could only play the team in front of them, however, and they’ve looked great doing it. Outside of the center position, the Celtics have a roster chock full of talented, athletic defenders, all of whom were moving in sync throughout the preseason.

They’re simply missing an anchor on the back line, or at least one that fits every matchup. Theis has the talent, but it would be surprising if he can hold up against elite-level size and athleticism. If he can do so just enough to let Boston’s swarming perimeter defenders make an impact, the Celtics may be better than anticipated. It’s hard to make that call based on preseason play, but we won’t have to wait long for a more intense test.

Boston opens its season facing off against the league’s biggest team - the Philadelphia 76ers - in less than a week.