This summer for Celtics, the kids were more than all right

Terry Rozier, who impressed with fearless late-game shooting, was one of several Celtics draft picks who played well in eight summer league games. Rick Bowmer/Associated Press

LAS VEGAS — When it was over Saturday, there was disappointment but also satisfaction. The Celtics lost at the buzzer to the San Antonio Spurs in the finale of their eight-game summer league schedule, and the players wanted to win the Las Vegas Summer League tournament.

Yet, the 4-1 record in Las Vegas and impressive play by all four of the team’s draft picks and free agent signee Jonathan Holmes offered encouragement heading into training camp.

Unlike many of the 24 teams at the Las Vegas Summer League, the Celtics didn’t pad their roster with seasoned international veterans and journeymen vying for one more NBA chance. They were mostly rookies and second-year players. Behind returnee Marcus Smart, the Celtics bonded with each other.

The rookies seemed to enjoy playing together, building chemistry and cohesiveness, knowing that much will be expected come October. The statistics weren’t overwhelming and most of the team’s rookies struggled from the field, but Terry Rozier proved he is fearless in the fourth quarter by hitting a go-ahead jumper against Portland followed by a tying 3-pointer against San Antonio in crunch time.

R.J. Hunter looked lost in Salt Lake City, the Celtics’ first summer league stop, but was able to regain his shooting stroke in Las Vegas. Jordan Mickey was effective in the paint, averaging 13.8 points and 9.8 rebounds in the five Las Vegas games. Even more encouraging for the Celtics was his impressive footwork and ability to hit midrange jumpers.

The Celtics will figure out their roster over the next 10 weeks. That’s why the David Lee trade has yet to be announced. They are trying to maneuver the salary cap to perhaps add another player, but also to clear roster space for younger players.

That’s what makes the situation with Holmes so difficult. Not only did the 6-foot-9-inch forward prove to be a solid rebounder and post scorer, he made 13 of 28 3-point attempts in eight games. The Celtics are overflowing with post players with the addition of Mickey, Lee, and Amir Johnson, but might be inclined to make room for Holmes, who was undrafted out of Texas but has shown he’s an NBA player.

The most challenging aspect of this Celtics rebuild is determining how many young players to retain. The team waived point guard Phil Pressey to clear up their backcourt, but allowing Holmes to sign with another team could be a mistake.

It’s easy to become overenthusiastic about summer league performances, but teams understand that second-round picks and undrafted players sometimes thrive in such situations and need to be secured or lost. That’s why the Hornets signed Kentucky guard Aaron Harrison to a deal and the 76ers did the same with Florida guard Scottie Wilbekin.

Having too many young prospects is a good problem to have. That’s how a foundation is built and stabilized. Team president of basketball operations Danny Ainge did not want to utilize all four of his draft picks, but he did so because trades weren’t available to attract veteran talent.

Marcus Thornton, the 45th pick in the draft, is likely headed to the NBADL or overseas, but the guard also displayed potential. There have been previous summer league disappointments such as Fab Melo or former second-round pick Colton Iverson, but this summer league didn’t produce any lemons.

“I was really impressed,” Las Vegas Summer League coach Micah Shrewsberry said. “That’s what I just told those guys, how happy I was for them with how they played, how hard they played, just thanked them for listening and the way they approached this week with us. We got a lot better.

“It’s a definite bonus and thrill for us going into the offseason. I told those guys to continue working, can’t be satisfied with what we did this week. Let’s get back in the gym. Let’s keep working on things that are going to get them on the floor.”

So the Celtics didn’t win the Las Vegas Summer League. But they left Sin City knowing that they took a step toward improvement. The free agency period did not work out as expected. The team was unable to attract a premium player, but the best way to ensure an All-Star considers Boston more seriously is to cultivate young talent.

Smart is one of those players, and Rozier wowed scouts during summer league with fearless play and clutch shooting. Hunter needs to get stronger but is a smooth shooter who plays solid defense. Mickey may be ready to contribute immediately. He played bigger than his size and is handy in the perimeter.

So consider summer league a success for the Celtics. They were able to get their rookies eight NBA games in front of large crowds, and most flourished in the moment. The next 10 weeks will be interesting in how Ainge builds the roster, but it’s evident that these young guys need to be part of the future — even if it means taking a step back in the short term.