The Celtics couldn’t have asked for a better start to their season, despite watching their nine-game winning streak come to an end against the Chicago Bulls on Monday night.

Boston dropped to 13-4 but that’s still good enough for the best record in the NBA through 17 games. Interim coach Joe Mazzulla has been front and center in helping create that success, captaining an offensive system that has the Celtics on a historic scoring pace nearly a quarter of the way through the season. His players have clearly bought into him as their new leader as well, lessening the impact of Ime Udoka’s suspension and expected eventual departure from the organization.

However, there is on area of his coaching where Mazzulla is living a bit too dangerously during his tenure and it surfaced again on Monday night in a double digit loss for the Bulls.

Mazzulla and the Celtics were clearly hungry for a 10th straight win and he made that apparent with his minutes management. After watching his squad fall behind by double digits early, Mazzulla shrank his rotation in the second half to eight players and barely played Derrick White and Sam Hauser within those eight while trying to erase a 20-point Bulls lead in the closing minutes of the third quarter.

Boston made some headway in the fourth quarter, trimming the lead down to eight on a few occasions but never poised a serious threat in the 121-107 loss.

On the surface, Mazzulla riding most of his starters to the end isn’t a big deal. The team clearly took pride in their nine-game winning streak and they were coming off two days off so fatigue shouldn’t be a big problem.

With that said, there is an exception to this line of thinking and that comes with 36-year-old Al Horford. The big man played a season-high 35 minutes for a regulation game in the loss as Mazzulla opted to cut Luke Kornet out of his rotation in the second half while chasing the win.

This is a risky bet for Mazzulla and the Celtics when it comes to the long term and it’s one that has continued for much of the year. Horford is averaging 31.6 minutes per game, his highest total since the 2017-18 season when he was a 31-year-old All-Star.

Horford still has tremendous value to Boston five years later but he also has a lot more miles on the tires now and quite simply shouldn’t be playing that much in a regular season game that the Celtics had a slim chance of winning for much of the second half.

Making matters worse was the fact that Horford wasn’t having a productive offensive game (0 of 9 from the field, 0 of 7 for 3-point range) despite getting the big minutes. Horford’s value comes just as much on the defensive end but riding him for big minutes on a night when he doesn’t have it also defeats the purpose.

The Celtics have one of the deeper benches in the league and even though their backup bigs are flawed with Rob Williams out, they should be trying to protect and preserve Horford at all costs. Resting him in back-to-backs has been a good start but playing him heavy minutes in long shot scenarios shouldn’t happen.

Mazzulla pulled Horford with five minutes left but he had already played 35 minutes.

Big minutes haven’t just been a thing for Horford either. Jayson Tatum (37.4 per game) ranks 4th in the NBA in minutes per game. Jaylen Brown (36 minutes per game) is 17th in the NBA and also on pace for a career high. Those guys have younger legs that can handle the extra workload but working in more rest for them isn’t a bad idea either. However, protecting Horford’s health, who remains an integral piece of this team that can’t be replaced easily, should be a bigger priority for Mazzulla at this point.

There will be plenty of more opportunities for Horford to get more rest once Rob Williams returns but Mazzulla should still take his foot off the gas a little more with his trusted veteran. Boston’s title chances down the road will require Horford being at his best in May and June and the Celtics should be doing whatever they can to ensure he gets there in that condition.