LAS VEGAS — Brad Stevens has been in meetings and traveling since departing Utah last Thursday, but was back with the Celtics’ summer league entry Tuesday night with interesting observations about some rookies who could contribute when the real games begin.

The Celtics’ coach is duly impressed with No. 3 overall draft pick Jayson Tatum and the progress of Ante Zizic. And he’s talking as if second-round pick Semi Ojeleye might be able to work himself into a role this season.

Of Tatum, Stevens said flatly, “He knows how to play. He can put the ball in the basket. But he’s had some things that I think have been good eye-openers for him, too, because this league is tough. Whether it’s people getting up underneath him, really playing him physically, figuring out what shot is the best shot to take at that time, and then just finding his spots, those are all things that you learn over time.

“I’ve been really encouraged by his defensive play,” the coach added after the 88-83 win against the Markelle Fultz-less Philadelphia 76ers brought Boston to 3-0 in the Vegas league, “and that’s something that, with his length and ultimately as he builds more strength, should be a positive.”

Zizic has played increasingly well, going for 12 points and 13 rebounds in just 18 minutes Tuesday.

“I thought part of Ante’s struggles in the first few games were because we were putting him in bad spots,” Stevens said. “I talked to the team a little bit when I got here about, if Ante’s got his guy sealed on the block, we have to throw him the ball. If Ante’s rolling to the rim, don’t throw it at his ankles; put it up in the air. And then you saw Demetrius (Jackson) threw a nice lob pass today and delivered it, and he dunked it.

“He does a good job, even if you throw a floater up there, of staying in the play and trying to get the rebound. But it’s hard to come in and all of a sudden you’ve been a roller and a post player your whole life, and we’re throwing you the ball at 27 feet and trying to be Al Horford. That’s not who he is, nor will we ask him to be that.”

The Croatian has played through a heavy schedule.

“He’s getting more comfortable every day, (but) I think he looks gassed, personally,” Stevens said. “His long year (playing in Europe) ended June-whatever … and he traveled over here on the 26th and started practice. I think he’ll benefit more from the next month than anybody else on our team.”

Stevens seemed perhaps more prepared for what Tatum and Zizic could do. Ojeleye, on the other hand, has opened the eyes of the coach and others.

“I think what he’s doing translates,” Stevens said. “That’s the thing with Semi. I didn’t know coming in that he could be matched up on 5s for possessions because of his leverage and his strength, but I thought the biggest key to winning the Lakers game was him guarding (7-foot-1 center Ivica) Zubac and stretching Zubac out. So his flexibility defensively is going to be enormous.

“I mean, I think that he will compete to be one of our better defenders right out of the gate.”

Flexibility will be a key, too, for second-year swingman Jaylen Brown, who suffered a bruised hip during Tuesday’s game. Brown said Stevens had told him to be ready to cover point guards and shooting guards, as well, this season, and the coach confirmed that he should be ready to do so when called upon.

“He didn’t spend a ton of time on 1s this year, but certainly he guarded 2s quite a bit as the season went on,” Stevens said. “And he had that stretch in the middle of the year where he was starting and we were just throwing him on guys just to throw him on guys and give him experience.

“So hopefully all that stuff pays off.”

The Celtics have played themselves into the Vegas winner’s bracket, and Stevens is enjoying the progress.

“It’s been fun to watch,” he said. “I watched a couple of the games on TV, and I think we can make strides and play better. I’m certainly encouraged by a lot of the things these guys can do individually, but a lot of them have a long way to go.”