Kyrie Irving, right, was dealt to the Celtics for a package that includes point guard Isaiah Thomas, left, Jae Crowder, 2016 first-round pick Ante Zizic (who signed with the Celtics in July and is technically an NBA rookie) and the Brooklyn Nets’ unprotected 2018 first-round pick. (Ron Schwane/Associated Press)
National NBA writer

The Cleveland Cavaliers found themselves in a seemingly impossible situation when it came to trading Kyrie Irving. Not only did the Cavaliers need to try to extract the kind of price a team looks to get to trade its star — some combination of cap relief, young players and draft picks — but Cleveland also needed to acquire talent to remain a championship contender.

There was only one team — the Boston Celtics — that had the ability to truly offer Cleveland that combination of present and future. The Celtics decided to do just that Tuesday night, getting Irving for Isaiah Thomas, Jae Crowder, rookie center Ante Zizic and the Brooklyn Nets’ unprotected 2018 first-round pick.

Rarely, if ever, do two teams at the top of the same conference — as the Cavaliers and Celtics were last year, and, barring injury, will be this year — make a trade. Rarely do two teams not only swap all-stars, but all-stars who play the same position. And all of that doesn’t even take into account the juiciest part of all: These two teams will meet in Cleveland on Oct. 17, the opening night of the NBA season.

Yet that’s exactly what happened here. And, from Cleveland’s perspective, it’s easy to see why.

This was the only trade newly installed Cavaliers General Manager Koby Altman could make for Irving. There was no way the Cavaliers could deal their star guard for a package centered only around future assets — not with LeBron James on the roster, and not after Cleveland saw James and Irving combine to lead the Cavaliers to a championship in 2016. Similarly, there was no way they could trade Irving for only present-day value, ignoring the possibility that James could bolt in free agency next summer.

This trade addresses both concerns.

Let’s start with the present. Thomas is an older (28 to 25), slightly lesser version of Irving: a virtuoso individual scorer who leaves plenty to be desired defensively. It also should be noted that Thomas, like Irving, isn’t afraid of taking — and making — big shots, as he proved time and again for the Celtics this past season, which is an asset Cleveland will need next to James deep in the playoffs. Crowder, meanwhile, is the kind of player James will love playing with: a bulldog of a defender who can guard several positions and space the floor, allowing Cleveland another option to play small around James — which has always been its most effective course of action.

He also gives the Cavaliers another player to utilize against Kevin Durant in a potential NBA Finals rematch — which would allow James to take a breather defensively, something he clearly needed as he got worn down by having to be extraordinary at both ends for 48 minutes of every game to give Cleveland a chance against the Golden State Warriors in June’s Finals.

Now for the future. Zizic, a first-round pick a year ago, is seen as a possible starting center down the road and could at least give Cleveland minutes behind Tristan Thompson during the long regular season. But the true long-term asset here is the Nets’ pick, one that should comfortably be inside the top 10 this season even as Brooklyn has begun to dig itself out of the massive hole it created by trading the rights to four No. 1 picks to Boston four years ago.

So if James does decide to leave next summer as an unrestricted free agent, Cleveland can begin its post-James future with a potential building block lottery pick at the top of the 2018 NBA draft, as opposed to having to wait a full year to reap the rewards of an initial awful season.

For Boston — a team that has spent the past few years accumulating assets, growing not only into a 50-win contender and Eastern Conference finalist but also becoming better positioned for the future than almost all of the league’s worst teams thanks to the Nets trade — it makes sense to deal for a young star they think they can keep long term like Irving, who is under contract for three more years (although 2019-20 is a player option).

The question that remains, however: Why would Boston let several players most around the league would believe are better talents — namely DeMarcus Cousins, Jimmy Butler and Paul George — go elsewhere in trades over the past six months for lesser returns than Cleveland got in this deal?

One possible answer is Boston fears the long-term status of Thomas’s injured hip, which saw his playoffs come to a premature end. Or perhaps the Celtics were simply higher on Irving — who is somewhere between 18 and 30 months younger than all three of those previously traded stars.

Regardless, the Celtics now have Irving and Gordon Hayward as their stars to build around moving forward, not to mention a pair of promising young forwards in Jaylen Brown and Jayson Tatum (June’s No. 3 overall pick) and either a top-five pick from the Los Angeles Lakers in 2018 or a lottery pick from either the Philadelphia 76ers or Sacramento Kings in 2019. That’s a foundation that sets Boston up to be good well past whatever decision James makes next summer.

That’s precisely why Boston was the only team that could get Irving out of Cleveland. And it’s why the Cavaliers pulled off a home run deal by finding the one trade that could give them everything they needed to trade Irving, both now and in the future, and then not hesitating to do so.

There’s a reason trades like this never happen in the NBA. It takes a series of circumstances lining up perfectly in order for both sides, which normally would be reluctant to deal with the other, to be willing to make such a move.