Mazzulla Won't Coach Boston's Opener — His Assistants Have Something to Prove
GOATIFYJoe Mazzulla is doing something unusual for Boston's first preseason game: he is giving the sideline to his assistants. Tony Dobbins will run the first half against Cleveland, DJ MacLeay will take the second, and Mazzulla plans to watch from the back with the video staff rather than direct every possession. It is not a change of head coach or a sign of trouble. It is a deliberate test of the people who help run the Celtics every day, and of what their boss might notice when he is no longer the loudest voice at courtside.
For a team beginning another season with a reshaped roster, the arrangement is a revealing experiment. The exhibition score will matter less than the decisions Boston's assistants make in real time and the lessons the whole staff can carry into the regular season.
The Assistants Have Earned a Bigger Stage
The arrangement is straightforward but uncommon at the NBA level. Dobbins will handle the first two quarters of the October 8 game in Cleveland; MacLeay will take charge after halftime. The team has not installed a new head coach, and Mazzulla has not surrendered control of its larger system. He has instead handed his assistants the one responsibility they cannot fully simulate in a film room: making the last call when the clock is running and the players are looking at the bench.
Both men entered the summer with legitimate ambitions beyond an assistant's chair. Dobbins interviewed for the Dallas Mavericks' head-coaching opening, while MacLeay was considered for the Portland Trail Blazers job. Their experience already extends to leading Boston's Summer League team: Dobbins did so in 2023 and MacLeay in 2024. Summer League gives a coach the whistle, the timeout decisions and a short development schedule. A preseason NBA game puts many of those same judgments in front of established veterans and an opposing staff preparing for its own season.
Mazzulla's choice also sends a message about succession and professional growth. Assistant coaches spend years developing schemes, scouting opponents and building relationships, yet the head coach receives most of the visible credit or criticism. A half of live responsibility offers an unusually clear audition without changing the franchise's leadership. Dobbins and MacLeay can demonstrate how they communicate a coverage adjustment, decide whether to change a lineup, or respond when a possession breaks down.
There is a practical benefit for Boston as well. A coaching staff that has rehearsed different leaders is better prepared for the inevitable moments when its normal rhythm is disrupted. The Celtics are not evaluating whether either assistant can become Joe Mazzulla overnight. They are giving two trusted coaches an opportunity to make decisions under game conditions, and then giving the entire staff more evidence about how those decisions worked.
Dobbins and MacLeay Bring Different Strengths to Boston's Bench
Dobbins and MacLeay arrive at this opportunity by different routes. Dobbins has been part of the Celtics organization since its video department years and moved into an assistant role in 2020. His professional playing career took him through Europe, where his defense became a calling card. That background is useful in a job that demands both tactical detail and the ability to translate a complicated instruction into something a player can execute on the next trip down the floor.
His influence has also been personal. During Jayson Tatum's recovery from an Achilles injury, Dobbins worked closely with the Celtics star as an individual coach. Players have described him as unusually patient, a valuable contrast in a staff known for demanding standards. That temperament matters when a timeout is crowded with opinions and an assistant needs to calm the room without lowering expectations. His work with Boston's players is part of why the preseason handoff feels earned rather than ceremonial.
MacLeay, meanwhile, has helped shape the team's defensive teaching and player development. He joined Boston after working in Philadelphia's coaching operation, climbed from player development into an assistant role and has worked closely with big men including Luka Garza. A 2026 look at the team's film-study habits illustrated how much of Boston's preparation happens away from the television cameras: coaches and players work through clips, positioning and small choices that can decide an entire possession.
MacLeay's previous Summer League assignment offered a glimpse of his priorities. He emphasized establishing the habits and standards of the senior team, not merely winning an exhibition tournament. That makes Thursday's assignment a logical next step. With a veteran NBA roster, he must decide which lessons are worth stopping the action to teach and which mistakes should be allowed to play out. His half against Cleveland is as much about managing people as it is about selecting a defensive coverage.
For Boston's players, none of this should feel like listening to strangers. The assistants have already helped develop their games, review film and run practices. The difference is that the familiar voices will now have final authority for a stretch of live basketball. That is precisely the experience a future head coach needs, and precisely the kind of feedback a well-run organization can collect before the results count.
Mazzulla Gets a Different View of His Own Team
The other half of the experiment belongs to Mazzulla himself. Rather than hover behind his assistants and correct every decision, he plans to watch with video staff and players who are not on the floor. That gives him a different view of the Celtics' communication, spacing and defensive organization. A head coach standing at the scorer's table sees the action through the demands of the next substitution or timeout; an observer studying the same possession from the back can focus on patterns that are easier to miss in the moment.
There is a reason to take that idea seriously. Mazzulla was named NBA Coach of the Year for 2025-26 after guiding Boston to a 56-26 record and the Eastern Conference's second seed. The team finished near the top of the league at both ends of the floor despite a season shaped by Tatum's extended recovery. Success at that level does not eliminate the need for fresh information. It can make a coach more willing to test a process before a meaningful game exposes its limits.
Boston's new season also comes with questions that cannot be answered by an exhibition score alone. Tatum is entering training camp with a healthier outlook after the long rehabilitation, while new faces such as Paul George and Mike Conley are learning the team's habits. A preseason game is the right environment to assess communication and lineup chemistry without treating each run as a verdict on the season. Dobbins and MacLeay can focus on their coaching responsibilities while Mazzulla tracks how the group responds to different instructions.
There is one more planned step. Lead assistant Sam Cassell is scheduled to handle the final preseason game against Philadelphia on October 16, extending the opportunity across the staff. That makes the Cleveland arrangement look less like a publicity stunt and more like a deliberate development program. The value is not that Boston has discovered a novel way to win a preseason contest. It is that the Celtics are testing how knowledge, trust and authority move through the organization when the usual hierarchy briefly changes.
Thursday's most revealing Celtics possessions may be the ones immediately after a timeout, when a player has to execute a new instruction and the assistants have to live with the outcome. Dobbins and MacLeay have spent years preparing for those moments without always owning the final decision. Mazzulla is giving them a controlled chance to own it now.
For Boston, the reward could be larger than one evening in Cleveland: better-developed coaches, more adaptable communication and a head coach who has seen his team from an angle he rarely gets during the regular season.
