“Why do we care so much?” one of the two characters in “King James” asks the other. It’s the second scene in Rajiv Joseph’s play, now making its New York premiere, and Shawn is posing the question to Matt, a fellow sports super-fan with whom he has cultivated a close friendship based primarily on their mutual obsession with basketball’s Cleveland Cavaliers. 

I’ll confess here that my own professional sports IQ registers in the single digits, and that I’ve sometimes wondered what leads people, among them friends and relatives I love and admire, to, as Shawn puts it, “waste their time and money and emotional well-being on a bunch of pro-athletes.” Of course, in being a fan — whether of ballplayers, musicians, or even, heaven forfend, politicians — we can all develop connections and conflicts that transcend the celebrated person or vocation at hand.

This is clearly what Mr. Joseph, a two-time Obie Award winner and Pulitzer Prize finalist for other works, had in mind when he conceived the bromance between Matt and Shawn, which begins in 2004. That was when the play’s titular superstar, Ohio’s own LeBron James, was named the National Basketball Association’s Rookie of the Year, after joining the Cavs at age 18, as the first overall pick of the previous year’s NBA draft.

We see Matt and Shawn next in 2010, when Mr. James infamously left Cleveland for the Miami Heat; the third scene unfolds in 2014, when the prodigal son returned to the Cavs, and the play ends in 2016, the year Mr. James completed his redemption (for some, at least) by leading the team to its only NBA championship in half a century of existence in what was, I’m told, one of the most spectacular final games in the history of the sport.

For Mr. Joseph, this celebrated and divisive trajectory serves as a prism through which to study the progress of his characters, essentially lonely young men whom we follow between the ages of 21 and 33, through the personal and professional ups and downs that define their own less glamorous lives. When they’re introduced, Matt, who is white, is tending bar while aspiring to run his own establishment; Shawn, who’s Black, is juggling a couple of jobs while trying to embark on a writing career.

Race figures heavily into the play, first emerging as a factor when young Matt, before learning anything about Shawn’s background, expresses surprise that the latter attended an elite prep school. “Saint Ignatius is full of rich Irish douchebags, and you don’t fit that profile,” Matt tells his new acquaintance, diplomatically. “You’re not like those guys. You’re like me.”

Yet Mr. Joseph makes it quite clear that Matt is not like Shawn. The first character’s white privilege is conspicuous from the start, both in his assumptions about Shawn and his tendency to be presumptuous and self-pitying. He refers repeatedly to “the problem with America,” in lines that “Abbott Elementary” star and theater veteran Chris Perfetti, under Kenny Leon’s nimble direction, infuses with both an easy comic facility and subtle poignance.

Shawn, who’s played just as adroitly by Glenn Davis — current artistic director of Chicago’s noted Steppenwolf Theatre Company, where “King James” had its first run — mocks but tolerates these qualities for a while. Yet when it’s announced that Mr. James is rejoining the Cavs, and Matt, still sore over his departure, remarks that the athlete “should have known his place,” Shawn is offended and infuriated on a personal level, and a decade-long friendship suddenly hangs in the balance.

As the very authoritative sports fan who accompanied me to a preview of this play noted, Mr. James’s cavalier (pardon the pun) manner of revealing his decision to leave his first team — “I’m gonna take my talents to South Beach,” he declared, during a live broadcast that Matt and Shawn both lament at length — was criticized in not dissimilar terms by followers of different skin colors. But it’s understandable that Shawn would read racism into Matt’s comment, and it certainly makes sense that Mr. Joseph would weave this dynamic into his contemporary, nuanced portrait.

Between scenes, recordings by Kirk Franklin, Usher, and Eminem underscore the tensions and camaraderie in focus, while before the curtain and during intermission, the animated DJ Khloe Janel holds court at a booth adorned with a small American flag. Where Matt may not express high hopes for our country, Mr. Joseph’s tone in “King James” is ultimately one of cautious optimism for its people, at least.