In hindsight, Brad Stevens probably shouldn’t have played Marcus Smart in the Boston Celtics’ penultimate regular-season game against the Orlando Magic.

At the very least, the Celtics coach shouldn’t have put Smart back into Sunday’s (meaningless) contest after the guard suffered an injury while colliding with Magic center Nikola Vucevic in the third quarter.

Yet both Stevens and Celtics president of basketball operations Danny Ainge on Thursday defended the team’s handling of Smart, who could miss Boston’s first two playoff series with a partially torn oblique muscle that’s expected to keep him sidelined for four to six weeks.

“I guess I could always go back and look and say, ‘Would I have played him again in that game period?’ ” Stevens told reporters Thursday at the Celtics’ practice facility, per MassLive.com. “But as you look around the league, there’s a lot of guys that played in the last two games or three games, and freak things can happen.”

To be fair, Sunday’s game at TD Garden wasn’t officially meaningless until just before tip-off. The Indiana Pacers still had an outside chance at securing home-court advantage for their looming first-round playoff series against the Celtics. It wasn’t until Indiana lost to the Brooklyn Nets on Sunday — barely before the Celtics’ tip-off — that Boston locked up the No. 4 seed.

“You have to play guys, and it was a good game, good competition,” Ainge told reporters Thursday, defending his coach’s decision-making. “You can’t go for a long period of time without getting reps and getting play, and the plan was to play those guys against Orlando and leading up to that game.”

“We didn’t know we had home-court advantage locked up until right before tipoff. So the guys were prepared and ready to play, and I don’t think Brad was planning on playing Marcus in the fourth quarter, but it happened in the third. You can’t put them in bubble wrap.”

Smart briefly stayed down on the court after running into Vucevic in the third quarter. Still, the 25-year-old — known for his toughness and defensive tenacity — convinced Stevens and the Celtics’ training staff he was OK to return to action.

After that, it didn’t take long before Smart fell back to the hardwood and missed the remainder of the game. Now, Smart will watch from the bench as the Celtics face the Pacers and could continue to do so until the Eastern Conference finals, should Boston advance that far.

“He told our trainers — and our trainers were talking to him the whole time — and what he said afterwards, he told me he didn’t really notice it until he bent his knees and got in a stance,” Stevens said. “So that’s when it didn’t feel the same. I have to listen to the training staff, I have to listen to our players, and Marcus was the one who gave the thumbs up on that.”

It’s no surprise Smart lobbied to return given his reputation as a hard-nosed competitor. And it’s also no surprise Ainge backed Stevens against potential criticism, citing the need to listen to the player when an injury crops up.

“Thank goodness he ran up the court one time and ran back and he knew he wasn’t able to play,” Ainge said. “I don’t put any blame on that. You always listen to the players. You always know Marcus is going to play through pain, and he couldn’t. Just like I certainly don’t question Coach Stevens for playing him, either.”

The Celtics and Pacers will begin their first round playoff series Sunday afternoon, with Games 1 and 2 taking place at TD Garden. Boston should be able to take care of business against Indiana, which is without its best player, Victor Oladipo, but Smart’s injury could cost the Celtics at some point later this postseason. And it’s fair to wonder whether the now-dicey situation could have been avoided with a little extra caution.

Just don’t remind Stevens and/or Ainge.

Thumbnail photo via Mark J. Rebilas/USA TODAY Sports