When Jayson Tatum tore his Achilles in the spring of 2025, the assumption across the league was that the Celtics would spend 2025-26 treading water. Most projections had Boston somewhere near the play-in tournament. Instead, the Celtics are 41-20 and sitting second in the Eastern Conference in March, and the clearest explanation is Joe Mazzulla’s coaching.
Boston beat Milwaukee 108-81 on March 2 without both Tatum and Jaylen Brown, who was out with an illness, holding Giannis Antetokounmpo to 19 points on 7-of-18 shooting in a game that was supposed to be a mismatch.
The March 2 win over Milwaukee without Tatum or Brown was the most complete example of what Mazzulla has built this season
Payton Pritchard scored 25 points with nine assists in the role he has grown into under Mazzulla’s system, which asks whoever is available to execute the same principles regardless of who is missing. Rookie Hugo González had 18 points and 16 rebounds against the Bucks, and the Celtics held Milwaukee to a season-low 81 points. That defensive performance without Boston’s two best perimeter players is the part that matters most. It suggests the system is doing the work, not just the talent.
Mazzulla has been direct about his approach. When asked about the timeline for Tatum’s return, he said, “I don’t operate on feel. I live by principle.” That is not a throwaway coaching cliché in his case. Boston ranks first in the NBA in defensive rating at 107.0 opponent points per game and plays at the slowest pace in the league at 94.7 possessions per game.
Mazzulla deliberately slowed the tempo to maximize every possession without Tatum’s scoring volume, and the defensive structure has been rigid enough to make that work.
Mazzulla has turned Queta, González, and the Vucevic trade into a roster that does not need Tatum to dominate
Neemias Queta has become a double-double producer this season and dropped a career-high 27 points against Philadelphia on March 1. González, a 2025 draft pick, has been fast-tracked into the rotation and looked like a veteran in the Milwaukee game.
Nikola Vucevic, acquired at the trade deadline, has slotted in as a passing hub out of the post that Mazzulla uses to pick apart defensive rotations. None of these players were expected to carry significant offensive responsibility this season. All of them are doing it.
The Celtics’ net rating of +8.3, second in the NBA, shows that this is not a team surviving on close games. Boston is beating teams comfortably and doing it without its best player and frequently without its second-best player.
The “gap year” prediction assumed the Celtics’ success was dependent on Tatum. Mazzulla has spent the season proving it is dependent on the system, and the system does not care who is in the lineup. That is why the Coach of the Year conversation has shifted from whether Mazzulla belongs in it to whether he is the favorite.