The Boston Celtics are a really, really good basketball team when Kyrie Irving is on the court. Which makes a lot of sense, because, well, he’s one of the best players in the NBA.

When Irving is off the court, however, it’s a totally different story, and the Celtics need to do something to fix that.

Boston currently is 13.7 points better with Kyrie Irving on the floor, according to Cleaning The Glass, and that never was more apparent than Thursday night in Boston’s 127-113 loss to the Houston Rockets.

During the first quarter, Irving and Marcus Morris kept the Celtics within arm’s reach of James Harden and Co., but when Irving went to the bench with three minutes remaining in the stanza everything went haywire.

The Rockets outscored Boston 26-14 during the 6:25 seconds of game time that Irving was on the bench, swelling their lead from three points to 15 during that time span.

It was more of the same in the second half.

After dueling with Harden for the majority of the third quarter, Irving headed to the bench with 1:48 remaining in the frame and the C’s trailing by four. By the time he returned with 8:53 remaining in the game, Boston was trailing by 12. The Celtics were outscored 18-10 in the 4:55 Irving was off the floor in the second half.

The disparity seemed even greater when compared to how the Rockets fared without Harden on the floor. When the reigning NBA MVP took his blow in the first half, the Rockets extended their lead from 11 to 16, outscoring Boston 16-11 in the four minutes he was on the bench. Harden left at the same time as Irving in the third period, and sat for a minute longer, watching his team grow their lead from four to 11 while he was wearing sweatpants.

Irving is a tremendous talent but he can’t be on the floor for all 48 minutes. Apart from Jaylen Brown, the Celtics’ bench was more or less absent Thursday night and it has shown a tendency to struggle when Irving isn’t out there running with them.

It’s a problem Brad Stevens must figure out how to rectify as 2019 approaches.

Here are more notes from Celtics-Rockets: 

— Irving scored 23 points and dished out 11 assists in the loss. He now has posted back-to-back 20-point double-doubles for the second time this season. He had no such streak during his first seven NBA seasons.

— There were quite a few technical fouls handed out Thursday night. Marcus Morris (two and ejection) and Marcus Smart both were T’d up for Boston, while Mike D’Antoni, Clint Capela and Chris Paul (from the bench) each received one for Houston.

— Boston also was crushed on the glass Thursday night as the Rockets outrebounded the C’s 54-38.

— After scoring 45 points against the Celtics, Harden now has netted at least 35 points in six straight games, which is tied for the third longest streak in the last 20 seasons.

Thumbnail photo via Troy Taormina/USA TODAY Sports Images