One of the most interesting NBA trades this century is complete. But forget how it impacts this upcoming season. What is truly at stake going forward are the legacies of all of those involved.

In agreeing to a deal that swaps Kyrie Irving for Isaiah Thomas, Jae Crowder, Ante Zizic and Brooklyn's 2018 first-round pick, the Cleveland Cavaliers and Boston Celtics have bet the reputations of nearly every person involved on how this shakes out.

This has always been the crux of LeBron James. He will make you or break you, give you glory or all-time heartbreak -- or both. But that magnifying glass and the spotlight that follows him everywhere has the same effect on those around him.

Now that impact will bring a sharper sense to how, years from now, we view the legacy of Irving. And Thomas. Don't forget seasoned Celtics general manager Danny Ainge and his unproven, rookie counterpart in Cleveland, Koby Altman. 

And ultimately, because things always come back to him in this league, the legacy of LeBron James.

Let's start with Irving. The would-be superstar is fresh off his divorce from James, and the schism between how those around the league view him -- true superstar, or a super sidekick who like many before him was enhanced by the gift of playing with LeBron -- will be crossed one way or another by Irving's time in Boston.

If he is in fact a prolific scorer whose defensive deficiencies translate to a flashy player unable to carry team to greatness, we'll soon know it. Boston is no rebuilding team happy to have a star in exchange for a coveted draft pick. Last year's top Eastern Conference seed has added Gordon Hayward and newly drafted, No. 3 overall pick Jayson Tatum. Kyrie is the missing piece or a swing and miss.

Irving can cement his place as one of the NBA's true premier players, or disprove it. He has left the LeBron nest. In Boston, we'll know just how far and high he can fly.

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Kyrie Irving, left, dribbles against Isaiah Thomas. The two stars were swapped in an NBA blockbuster trade on Tuesday. Ken Blaze / USA TODAY Sports

This blockbuster trade means Thomas, too, will face a verdict on just who he is. An undersized allusion that burst to the NBA forefront on a Celtics squad in desperate need of a volume shooter, or a deserving all-NBA player whose diminutive size has kept him undervalued and underappreciated? Playing with James may not always be easy, but it can be revelatory. 

If Thomas is the second (or even third) act in a three-star drama that again makes the NBA Finals without a seeming hitch or step backward, many of us may have to reevaluate how highly we regard him. But if he's clearly no Kyrie -- and that, fair or otherwise, becomes a storyline in Cleveland -- watch out. There's no vengeance or angst like the kind that follows around LeBron James and his teammates when things go badly.

Then there's the general managers. Ainge has been gilded with the notion his basketball genius is too deep and true for most of us to fathom until much, much later. That franchise-changing trade with the Nets and hiring of unproven college coach Brad Stevens? Strokes of greatness, yes, but they won't matter much if his moves the past few months turn into duds.

Trading away this past No. 1 overall pick and moving down to draft Tatum had best be the right call, because it was a key domino in moving to radically change a Celtics team that made last year's NBA Eastern Conference Finals. Crowder, a criminally underrated player, is off to Cleveland in this deal. Avery Bradley, another sensational and under-the-radar talent, is in Detroit. I.T. is gone, too. And the highly coveted unprotected 2018 Brooklyn pick could turn into a transcendent talent next summer.

That's a lot to gamble on Irving, particularly when, say, Jimmy Butler could have been had for less.

Then there's Altman, the Cavs' young, smart general manager. He stepped into the breech after owner Dan Gilbert couldn't or wouldn't reach a deal with former GM David Griffin. Altman's task from Day One was daunting: Put a club on the floor this upcoming season capable of winning it all and keeping -- if he's willing -- LeBron in Cleveland; simultaneously have a plan to build without James if he bolts for a team like the Lakers and leaves Cleveland in wreckage. And do all that with "As The NBA Turns" playing out each day in his back yard as his two stars head off for a public and messy breakup and make any leverage for Irving a bad joke.

Altman couldn't have swung a better outcome given those challenges. The Brooklyn pick is a bridge -- a big one -- to a LeBron-less future, if that's what's coming. But Thomas and Crowder (and Zizic, maybe) make Cleveland able to be very, very good again. 

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Cleveland Cavaliers' LeBron James, left, will be playing alongside Isaiah Thomas next season.

It's a stunning haul, all things considered.

And it won't mean a damn thing -- at least not for Altman -- if come next May if Boston has bested Cleveland in the playoffs, and Kyrie Irving is clad in green and headed back to another NBA Finals.

Even James will be judged by what come's next. He couldn't make it work with Kyrie. He may bolt for another team next season. Or not. Either way, if Cleveland and LeBron come up short next season, the idea of LeBron the invisible hand will turn into a punchline. The player still will be a legend, of course, but the shadow GM will be remembered as a guy who should have let Riley be Riley and know his lane.

Those are the massive stakes when dealing with LeBron James, the expectations his greatness deliver and now a trade involving the top two teams in the Eastern Conference and a pick and players capable of shifting the fortunes of everyone involved.

The deal is done. But the long-lasting consequences are just beginning.