After the Celtics’ disappointing regular-season run this season, Tatum’s star hasn’t been as bright so far in these playoffs as Boston faces the Indiana Pacers in the first round. He did not make the leap many had thought he would: While he improved as a rebounder and passer, his shot selection led to more long 2-pointers, causing his true shooting percentage to dip from .586 in his rookie campaign to .547 this year, placing him below .560, the league average.

He increased his frequency of midrange jumpers but decreased his accuracy in making them: 37 percent, down from 44 percent. Many of his advanced metric statistics, including win shares per 48 minutes, value over replacement player and box plus/minus, were worse this year.

Tatum finds himself in an unusual spot, compared with fellow N.B.A. sophomores like Utah’s Donovan Mitchell and Philadelphia’s Ben Simmons. The better Tatum plays, especially in this postseason, the more likely he is to be linked to trade rumors, particularly those involving Anthony Davis, the New Orleans Pelicans star who has requested a trade that could shift the competitive balance in the N.B.A.

Several college starters in this year’s Final Four were older than Tatum. But if he cannot live up to the hype he created in last year’s playoffs — that is, if he becomes just another guard — the Pelicans may be more likely to accept a package from the Los Angeles Lakers or another team besides Boston. At the same time, if Celtics point guard Kyrie Irving opts for free agency this summer, the future of the franchise may rest on Tatum’s shoulders. At barely 21, he’d be the alpha.