Aaron Nesmith stepped into his old role for a moment. With the Pacers ahead 75-71 and his shot off in a 1-for-3 start, he stood along the baseline against former teammate Derrick White and drew a charge. Indiana went on to score on four of the next six possessions to close the third, building an 11-point lead the Celtics would not be able to surmount.

Nesmith’s 11 points in the fourth quarter, a career high, played a significant role in securing the victory that set up the Pacers’ run to the In-Season Tournament final. Boston saw a different Nesmith than the one they traded for Malcolm Brogdon last summer — stronger, able to score off the dribble and capable of rotating inside to block Jayson Tatum at the rim.

Nesmith emphasized necessary repetitions for his success in Indiana after departing the Celtics, getting opportunities to make mistakes, take shots and play longer stretches in games. It made him a new player and the Pacers a new team — the best offense in NBA history to begin this season. And on Monday, emphatically victorious over an older Celtics team. That’s who Boston is now — older.

The older Celtics couldn’t provide Nesmith that opportunity, instead utilizing him, Robert Williams III and other young players plus draft picks to consolidate the roster over the past two years. It built the kind of team capable of a 15-5 start and championship favorite status, but it also likely shrunk their contention window with the ascending Pacers, Thunder, Magic, Rockets, and others growing out of their rebuild stage and on Boston’s heels.

Brad Stevens still hasn’t drafted a first-rounder as general manager. That’s not a knock on the former head coach and current President of Basketball Operations, as the Celtics needed talented veteran infusions after mediocre drafts late in Danny Ainge’s tenure.

It’s acknowledging the future paths charting for teams that focused on the draft and others who spent all their picks making trades.