Joe Mazzulla is expected to be named NBA Coach of the Year on Tuesday night, a recognition that would place the Celtics coach at the center of another milestone only a year after he guided Boston to the franchise’s 18th NBA title. The award would cap a rise that began far from the league spotlight, when he was a freshman point guard at Bishop Hendricken in the 2002-03 boys’ basketball season.

Jamal Gomes, who coached Mazzulla at Bishop Hendricken, said he saw signs early that the guard understood the game in a way most teenagers did not. “I remember his first game he was doing things that other guys on my team couldn’t do,” Gomes said, pointing to Mazzulla’s “level of vision, understanding, awareness, all that.”

That awareness showed up in the details. Gomes said Mazzulla could read defenses, identify strengths and weaknesses and even steer the offense from the floor. “He had that level of awareness at a very, very young age in terms of understanding the strengths and weaknesses of opponents, the game plan, the different offenses and defenses,” Gomes said. At times, Gomes recalled, Mazzulla would lean over and offer the kind of suggestion that sounds ordinary in an NBA huddle but was remarkable coming from a high school freshman: “Coach, you know, they’re in a matchup zone right now. Maybe we should try this offense,” he remembered him saying.

Mazzulla guided Bishop Hendricken to state championships in each of his final three seasons and was the state player of the year as a junior and senior. He finished a four-year playing career at West Virginia in 2011, then spent five seasons as an assistant at Division 2 programs Glenville State and Fairmont State. He later spent a year with the Celtics’ G League affiliate in Maine before returning to Fairmont as head coach in 2017.

By then, the profile Gomes had seen years earlier had become harder for others to miss. “Right off the bat I said, ‘Listen, he’s special,’” Gomes said. When he later spoke with Brad Stevens, Gomes said the Celtics executive answered simply: “I know.” He also recalled watching Mazzulla on the sideline and thinking, “Wow, he looked like he’s been an NBA head coach for 10 years.”

Mazzulla joined the Celtics’ staff under Stevens in 2019 and became interim head coach in September 2022 after Ime Udoka’s suspension for having an improper relationship with a subordinate team employee. He was elevated to the full-time job in 2023 and led Boston to the title in his second season. Tuesday night’s expected award would underline how quickly that transformation happened, but it would also serve as a reminder that the reputation behind it was built long before he reached the NBA.

Gomes put it more plainly: “Joe Mazzulla is special.”