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A look at one major trend in the Celtics' first-round series against the Bulls after Boston took a 3-2 lead in the series Wednesday with a 108-97 victory in Game 5.

The Celtics' on-off splits with Isaiah Thomas on-court defensively during the season were hilarious. They were 8.9 points worse per 100 possessions defensively with Thomas on the floor, with an awful 108.9 defensive rating when Thomas was on-court. But in this series, amazingly, that's turned around. The Celtics are 9.8 points better per 100 possessions defensively with Thomas on the floor, with a very respectable 102.8 defensive rating.  

The big turnaround? How he and Avery Bradley have played together. 

In the regular season, they bled, with a 107.9 defensive rating together. Against the Bulls, it's been a great 102.9. And when Bradley leaves, Thomas' defensive rating holds firm at 102.8. 

They've held Jimmy Butler in check, with Butler shooting 34.9 percent from the field when those two are on the court. In Game 5, in particular, Thomas did a great job of containing Butler, sealing off the baseline on his drive and delaying Butler's attack until help could arrive. Bradley got beat on a lob entry pass to Butler for a score; the next time the Bulls tried it, Bradley snatched it away and the Bulls never really went back to it:

Rajon Rondo's absence surely plays a factor here. All these numbers were reversed before Rondo went down after Game 2. But the Celtics have also simply played better. They are winning the battles they need to win, with Thomas having one of the best defensive ratings on the team. If Chicago can't take advantage of Thomas' size and defensive liabilities, they aren't going to win this series. 

After Game 5, Isaiah Thomas joked he's "First-Team All-Defense" and Bradley said Thomas is underrated. Whether it's the Bulls' failures or his own defense, the results make those comments way less absurd than you'd think.