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Isaiah Thomas’ defense is a problem the Celtics must keep hiding

Even Thomas admits he’s not the best defender. How does Boston compensate?

NBA: Playoffs-Boston Celtics at Chicago Bulls Mike DiNovo-USA TODAY Sports

We saw the curse of the postseason press conference when Russell Westbrook tensely interrupted a reporter’s question directed to his teammate, but there’s a bright side. You’d also never get this type of interruption from Isaiah Thomas when he butted into a question asked to Avery Bradley about a couple big defensive plays Thomas made.

“I’m first team, that’s why, all defense,” Thomas joked before the question had even been completed.

“Yeah, I mean, he’s underrated,” Bradley replied. “He has to be one of the better guys —”

“Don’t hype me, don’t hype me,” Thomas interrupted, smiling. “They say I’m the worst defender in the league. I’m fine with being the worst defender.”

“He did a fine job tonight,” Bradley said.

This could be interpreted at face value as Thomas admitted he agrees with those people, but it seems more like he’s being facetious and just playing along with their narrative.

But the truth is Thomas isn’t a good defender, and that’s always going to be one of his limitations as a 5’9 player living in a world where most point guards are a half-foot taller than him. The question is how bad Thomas has been, and whether the Celtics can get over his weaknesses on that end.

Boston has actually been better defensively while playing Thomas this postseason.

With Thomas on the floor, the Celtics sport a 102.8 defensive rating, something that plummets to 112.5 when Thomas is sitting down.

That might not mean anything, because five games isn’t nearly a strong enough sample size to reverse an 82-game trend. In the regular season, Boston was nine points better defensively whenever Thomas sat on the bench. (In fact, their 99.7 defensive rating would have easily been best in the league.)

What might be happening is how the Celtics are playing Thomas. Seven of the eight most played five-man units involving Thomas have also included Avery Bradley, Al Horford, and either Marcus Smart or Jae Crowder. All four are excellent defenders, and that puts them in position to cover for Thomas if he needs the help.

Another obvious factor is Chicago not having a scoring point guard. Rajon Rondo wasn’t that, though his seven offensive rebounds in the first two games before he broke his thumb had to come from somewhere. To replace him, the Bulls have used Isaiah Canaan, and he has surprisingly scored 13 points in both Games 4 and 5.

That’s not a lot, but you can see moments where he burns Thomas defensively.

Thomas lost track of where Canaan is, didn’t stop him from getting baseline (a fundamental defensive principle), and got scored on. Here’s another instance.

After a switch, Thomas ended up on Wade, someone who is seven inches taller than him. Even when he missed the shot, the putback over Thomas easily saved the possession.

Chicago is attacking Thomas, so Boston is trapping and scrambling.

Several times, Jimmy Butler would initiate a pick-and-roll with Canaan as the screener, specifically designed to put Thomas in a defensive position.

This didn’t always work perfectly. Here’s an example of Chicago breaking a high Butler trap by connecting with a cutting Dwyane Wade.

Still, this is mostly an innocent mistake, with Thomas and Smart not realizing they were both scrambling to the open man until it was too late. Given another star player’s defense in this series, Thomas’s cross-court sprint to attempt to close out on Nikola Mirotic is appreciated.

However, Boston also has to know that this defense has a couple special advantages going up against Chicago.

  • Thomas can start every possession on a player he can guard adequately.
  • When Canaan is involved in the pick-and-roll, the Celtics aren’t very worried about him as the screener.
  • The Bulls were bottom-10 in three point makes, attempts, and percentage this season, so Boston has some luxury of leaving players open.

So yes, this strategy has worked great, and that’s a huge reason why Boston is suffocating Chicago’s offense while he’s on the floor. It doesn’t mean he’s a good defender, but the Bulls’ weaknesses allow for Boston’s defensive countermeasures.

What will the Celtics do in the next round?

It’s a fair assumption that Boston will advance. They may be a weak No. 1 seed propped up by an overachieving regular season, but they still should beat any No. 8 seed that heads their way. They won twice in Chicago already this season, and now they head into Game 6 looking to close out the series.

Washington and Atlanta are also playing a first-round series, though, with the Wizards up three games to two on the Hawks. They’re the higher seed and should also be expected to win this series, especially with the one-game lead they retain now. It’s still hypothetical, but let’s imagine the Wizards going up against the Celtics.

You can start Thomas on John Wall, who can just roast him in isolation, or on Bradley Beal, who can do the same and shoot over him. Any pick-and-roll action that Wall tries to run will be trapped heavily, but Washington is a better shooting team than Chicago. Those are the immediate concerns that come to mind when you wonder how the Celtics will hide Thomas, who is so incredibly valuable on the other end that you need him playing damn near 40 minutes each night.

In the regular season, Boston survived this with the same, harried, switching defense that we’ve seen so far, but will that work in a seven-game playoff series?

It might, but only if Thomas is able to prove he’s not the worst defender in the league.