SAN ANTONIO — Two and a half years ago, when Marcus Smart was looking to see where he would land in the NBA draft, there was no shortage of those offering testimonials for the 6-foot-4 guard before the Celtics took him sixth overall.

Teams sought the opinions of those who had worked with him, knowing that those who had grown closer to Smart at Oklahoma State might understandably be a little biased in their assessments.

Therefore, one of the stronger voices emanated from the guy who coached Smart during two summers with the U.S. national yeam — the under-18 crew before his freshman season and the under-19 squad the next year.

It was the same guy who Marcus Smart nearly beat Sunday night in Oklahoma City.

Billy Donovan, the University of Florida coach when he and Smart were brought together, had a consistent message for scouts and general managers who rang him up for his thoughts.

Donovan liked Smart. A lot. Still does.

Though maybe he didn’t like being so correct when Marcus was going for 11 points, six rebounds and nine assists — and helping force Russell Westbrook into seven turnovers — against his Thunder.

Oklahoma City came back from 13 down to win by 3, but it’s instructive to note that Smart was a game-high plus-11 in his 36 minutes.

It’s no surprise to Donovan, who in 2014 was telling people how hard Smart worked, even in practice — and especially when there was an element of battle to the drills.

“I think the one thing I always felt — and this is not being critical of Marcus; this is just, I think, for his development — is that he’s a guy that thrives more in competitive situations,” Donovan said. “And I always felt like if he could take that competitiveness to skill work — his shooting, his ballhandling — the sky’s the limit as to how good he can be.

“The thing that I was so impressed with was any time we did anything competitively, the whole disposition in the gym totally changed.

“He has got a great team awareness. He’s great with the guys. He’s got great leadership qualities. But he’s a guy that enjoys practice when there’s score being kept. When there’s a score being kept, he is on and he plays and he’s relentless. I really appreciated being around him for two summers to see that.”

There are still times when Smart’s sense of competition can get the better of him and lead him into quick shots. But it is also clear that he’s taken giant steps toward being able to handle the responsibilities that come with being an NBA point guard.

Even though some of the plays didn’t result in a personal stat for Smart, the Celts were never better Sunday than when he was driving and finding cutters or passing the ball out against a Thunder defense he had drawn out of position. If not directly from his action, then maybe a pass or two later, the C’s would have an open shot.

As for the numbers, Smart’s scoring (10.0) and assists (4.2) are up, and his fouls (2.3) are down. And this is in 28 minutes a game.

“He has that ability to run a team, and he’s getting better at it,” Jae Crowder said.

“He’s done a good of keeping that edge on being a feisty player and being smart at the same time. I think it’s still a process for him, an ongoing process, and it can be hard because he’s splitting time at backup point with Terry Rozier when Isaiah’s back. So I think this time with Isaiah (Thomas) being out is really helping him.”

When the Celtics are back at full strength, an improved Smart at the point will allow Thomas to play more off the ball and better focus on his scoring while Smart reads the floor.

“And that’s what we need,” said Crowder. “I feel like in the playoffs last year, we did that a little bit, and I think Marcus is a lot better now than he was last year playing the point and running things from that position.”

The Celtics are still awaiting word on whether Thomas will be back from his groin injury for tomorrow night’s game against the Spurs. But coach Brad Stevens has stated his hope that the early injuries to the club will pay dividends with players getting more opportunities, and in the case of Smart the last three games in Thomas’ absence, that appears to be the case.