He counseled arena executives on what kind of music to play during games. (“Less Jersey,” he urged, pushing niche artists like Santigold over old favorites like Bon Jovi.) He even coached them on how to screen patrons for weapons without appearing too heavy-handed. (“Be mindful,” he advised oracularly, “and be sensitive.”)

In the two and a half years since groundbreaking, as taxi-roof advertisements promised “All access to Jay-Z,” and sponsorship salespeople trumpeted how “hip and cool” he and his wife, Beyoncé, would make the arena, he and the Nets have effectively written a new playbook for how to deploy a strategic celebrity investor.

If it has been done elsewhere — see Usher with the Cleveland Cavaliers, Will Smith with the Philadelphia 76ers, and Jennifer Lopez and Marc Anthony with the Miami Dolphins — no team has come close to making as much out of a famous part-owner.

And none of the dozens of other current and former part-owners of the team have played so public a role — not Robert E. Rubin, the former Treasury secretary; not Mary Higgins Clark, the best-selling author, though she read to children at a Nets literacy event.

“He is it,” Mr. Ratner, the developer, said in an interview. “He is us. He is how people are going to see that place.”

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