Joe Mazzulla has never exactly carried himself like a conventional NBA coach. The latest footage from Las Vegas helps explain why.
MMA reporter Ariel Helwani recently watched the Boston Celtics head coach train with Eric Nicksick at Xtreme Couture, and the video quickly drew attention for two reasons. First, Mazzulla is in outstanding shape. Second, he is clearly not treating mixed martial arts like a celebrity fitness class.
Helwani described Mazzulla as someone who has genuinely put in the work, calling him “far more than just a fan of the sport.” Even Helwani, a devoted Knicks supporter, admitted the Celtics coach deserved credit after watching him move through the session.
The footage shows a lean, muscular Mazzulla working with real intensity. He moves comfortably, listens closely and appears fully engaged in the technical details of the training. There is none of the stiffness usually seen when a famous guest steps into a fight gym for a promotional appearance. Mazzulla looks like someone who has spent years learning how to operate there.
Had the chance to speak with Celtics head coach Joe Mazzulla and watch him train with the great @Eric_XCMMA.
Really fascinating to hear how much MMA has influenced the way he coaches.
He’s clearly put in the work himself. Far more than just a fan of the sport.
Hard to admit as… pic.twitter.com/AIp1vYigxd
— Ariel Helwani (@arielhelwani) July 14, 2026
That is because he has.
Mazzulla told Helwani that he has trained in MMA for roughly four or five years and even seeks out workouts while traveling with the Celtics. He also revealed that he entered a jiu-jitsu tournament two summers ago. This is not simply a coach who watches UFC events from his couch. It has become a serious part of his physical routine and personal development.
More importantly, Mazzulla has carried lessons from combat sports into basketball.
He has studied how MMA coaches communicate with fighters during rounds, when too much information can become a distraction and a few precise words can make the difference. Mazzulla explained that he asks Nicksick about what should be said during the action and what is better saved for the break between rounds. The comparison to NBA coaching is obvious: during tense moments, players rarely need a lecture. They need the correct instruction delivered clearly and at the right time.
That philosophy fits Mazzulla perfectly. His Celtics teams have often emphasized composure, preparation and responding to pressure rather than attempting to avoid it. He has previously used fight imagery and combat-sports concepts to teach players about staying calm in uncomfortable situations. To him, an opponent’s run, a hostile arena or a difficult playoff possession is not something to fear. It is a position to understand and escape.
The comparison is deeper than toughness. MMA forces competitors to solve problems while exhausted, under pressure and with an opponent actively trying to take away their preferred options. Basketball may not involve chokeholds, but playoff defense can create a similar mental challenge. Your first action disappears, the crowd is roaring, the clock is moving and the game still demands a clean decision.
Mazzulla clearly sees value in that environment.
The video also adds another chapter to the growing legend of “Psycho Joe,” a nickname built around his intensity, unusual motivational methods and fascination with competition in its most uncomfortable forms. At times, that reputation can sound exaggerated. Then footage emerges of the Celtics coach looking completely at home inside one of Las Vegas’ best-known MMA gyms, and suddenly the stories feel much easier to believe.
