LAS VEGAS -- Five days after LeBron James announced his decision to join the Los Angeles Lakers and about five minutes before his team took the floor for its first summer league game, Cleveland Cavaliers general manager Koby Altman reflected on the end of an era.

"When you first get hit with it, there is a level of hurt," Altman told a small group of reporters underneath the bleachers at the Cox Pavilion. "You're hurt because of what you went through for the four years with him and what he meant to us. But I was extremely thankful at the same time. I realize what we accomplished this year and the last four years, and we did a lot. I mean, it was four incredible years led by him, and I'm very thankful for the years he gave our team, this organization, the city."

Altman said he found out James was L.A.-bound when he got a call from James' agent, Rich Paul of Klutch Sports, on Sunday evening, shortly after Klutch released the news on its Instagram account.

Altman, James and Paul shared a phone call when free agency officially opened at 12:01 a.m. ET Sunday. Unbeknownst to Altman, after finishing the phone call, James was about to embark on a three-hour, in-person meeting with Lakers president Magic Johnson at one of his Brentwood, California, homes.

"I didn't know that was going on," Altman said. "I didn't know that was going on."

Still, Altman said he believed Cleveland had a chance to keep James.

"At that time, thought we were still in the mix, obviously," Altman said. "I think he was still going through his decision-making process. But found out sort of like you guys found out."

After taking the call from Paul on Sunday, Altman speed-dialed the Cavs' remaining veterans -- Kevin Love, Tristan Thompson, Kyle Korver, JR Smith and George Hill -- to inform them that he wants them all back next season to build a competitive club in James' absence.

"I think the Kevin piece is important," Altman said, prioritizing Love among that group. "Kevin is an All-Star, and you don't get better by moving Kevin. Kevin's been incredible for us for four years, and he wants to be here, and to me that's a big part for guys that are here and the guys that we're going to acquire, is that they want to be here and be a part of this new chapter and culture that we're creating.

"So Kevin has a big place in our franchise, and I don't think you get better by moving him. I think we'll explore opportunities with the roster in general, but as far as Kevin goes, I don't see how you get better doing that."

As for some of Cleveland's young pieces, Altman spoke of the team's plans to offer an extension to Larry Nance Jr., whom the general manager called "part of our core."

"He's going to be here for a while," Altman said, adding that he expects to retain restricted free agent Rodney Hood, as the Cavs have already tendered a $3.4 million qualifying offer to him for next season.

"I don't think it was anything we did right or we did wrong. I think this was a decision largely for him, and he deserved that." Cavs GM Koby Altman on LeBron James' departure

Cavs coach Tyronn Lue also used the word "hurt" in describing his reaction to hearing that James was leaving Cleveland.

"I didn't expect it. You know, when I saw, I was shocked and hurt a little bit by the decision," Lue told NBA TV during its Cavs-Wizards broadcast. "But like I said, we talked, and he said that I'm his favorite guy. He loved being coached by me. He loved the four seasons we had together, and that this decision was totally just a decision for himself and his family. I can live with that."

While Altman has been fielding calls about Cleveland's assets and potential ways to improve, he does not expect to add so much salary that the Cavs would be in the luxury tax again. Cavs owner Dan Gilbert spent nearly $130 million in luxury taxes in the past three seasons -- all 29 other NBA owners combined to spent $131 million in luxury taxes -- and 2018-19 should give the team a chance to reset the escalating tax by coming in below the threshold.

"I'm not saying we're definitely not going to go into the tax, but it's interesting now sort of being below it," Altman said. "It's a weird feeling to sort of be below that. Be like, oh, we have some more flexibility now, and it's an interesting thing to look at."

Although the Cavs won't be spending as fervently as they have in the past, Altman said he is reluctant to enter into next season planning a full rebuild process. The Cavs would have some incentive to tank; if they finish in the bottom 10 in the league, they keep their first-round pick, but if they finish in the top 20, that pick goes to the Atlanta Hawks. But Altman said he expects the Cavs will be a team that will be trying to win.

"I think what's exciting for us is, Coach is really excited about this new chapter, this new era of Cavaliers basketball, where we get to develop young guys and have some enthusiasm, have a new style of play, see what that looks like and really give a genuine effort to compete and overachieve," Altman said. "And we'll see."

Altman also discussed Jordan Clarkson, Cedi Osman and the Cavs' No. 8 pick, Collin Sexton, who scored 15 points on 4-of-12 shooting in his summer league debut Friday. They might not be as well-known as players James could be playing with in L.A., such as Rajon Rondo, Lance Stephenson, JaVale McGee and possibly Kawhi Leonard, but to Altman they still represent excitement for the Cavs.

"I thought that for us, our momentum as an organization, as a franchise, was heading in the right direction. And I still do. I don't think it was anything we did right or we did wrong," Altman said, referring to what played into James' decision to leave. "I think this was a decision largely for him, and he deserved that. He deserved to make this decision for him and his career and what he wanted to do.

"So we can't take it personal. We're not bitter. We're thankful and happy that he spent the last four years with us, and again, I personally have a lot of gratitude for what he did for my career as well, what he's meant for me. I have a championship ring. That's an incredible thing that we accomplished. So, no, we're very thankful."