If the Celtics are better with Derrick White on the floor, why did the guard sit so much in crunch time?

After sitting for much of crunch time Sunday night, Derrick White was back in the Celtics' starting lineup Monday night and driving on Darius Garland and the Cavaliers.Ron Schwane/Associated Press

CLEVELAND — By many advanced metrics, Celtics guard Derrick White has been the team’s most valuable player this season. Boston entered Monday night’s game against the Cavaliers outscoring opponents by 10.3 points per 100 possessions with White on the court, the best net rating on the team.

But Sunday’s double-overtime loss against the Knicks was another instance in which White was not on the court very often when the game mattered most. He played a total of just 6 minutes, 11 seconds over the fourth quarter and two overtimes, out of a possible 22. And three of those minutes came because Marcus Smart fouled out during the second overtime.

Celtics coach Joe Mazzulla, who has enthusiastically embraced advanced statistics during his first year in the top job, admitted that may have been an error.

“It’s probably a coaching fault of mine [Sunday],” Mazzulla said prior to Monday night’s 118-114 loss in overtime to the Cavaliers. “I probably should have had him in at the end of the game. And so when we have the majority of our roster, balancing that out and trying to get the best players on the floor is important. Rewatching it [Monday] there were definitely moments when we could have had him on the floor. So, when he’s on the floor we’re a really good team, and we need him to be confident and aggressive on both ends.”

Against the Cavaliers, White played all but 2:34 of the fourth quarter and the full five minutes of overtime.

Mazzulla said he considers several different factors when trying to determine a crunch-time lineup.

“It’s difficult assessing what’s the most important thing at that time,” he said. “Is it offense? Is it defense? Is it matchups? Is it rebounding? Is it individual defense? So I think just trying to diagnose what those segments of the game need to be able to make that decision.”

Tatum, Horford out

Celtics forward Jayson Tatum missed the Cleveland game due to a knee contusion. Mazzulla said he does not expect Tatum to miss more than one game because of the injury.

Forward Al Horford, who has yet to play in games on back-to-back nights this season, sat out due to back soreness, and center Robert Williams remains sidelined with a strained hamstring. Guard Malcolm Brogdon returned after missing two games because of foot soreness.

Smart’s better with age

Smart, the longest-tenured Celtic, turned 29 on Monday. The Celtics selected the guard with the sixth pick of the 2014 draft, and Mazzulla said he’s been impressed by Smart’s growth over the years.

Smart had 11 points and five assists in Monday's loss.Steven Senne/Associated Press

“He’s one of our emotional leaders and when he’s playing at a high level, he has a beautiful ability to control the game and control the team and the offense and the defense,” Mazzulla said. “One of the things he’s really grown this year is doing that. He does such a good job of controlling both ends of the floor.

“I love having him and it’s important he knows how important he is from a leadership standpoint to our team.”

Back to work

The Celtics dropped to 8-2 in the second game of back-to-back sets. Prior to the loss, Mazzulla said the team has maintained a consistent mind-set regardless of the situation.

“Just move on to the next game,” he said. “Be the tougher team and be as detailed as we can throughout the game knowing that we will hit tough stretches because of [playing the previous night], but we just have to work through it.”