The free-agent slugger is hoping for a new 10-year, $300 million contract with the Yankees. While most pundits expect him to get only about half of that, or perhaps end up with a different team, it’s anyone’s guess as to what he’s worth. And whether he lands a mega-deal will be the first major indication of future viability for Roc Nation Sports, the new sports agency launched by businessman Sean Carter (you may know him better as rapper Jay Z).

The budding agency, which Carter launched in April, has quickly built an impressive roster: In addition to its first client Robinson Cano, it has since signed NBA star Kevin Durant, Giants receiver Victor Cruz, Jets rookie quarterback Geno Smith, and WNBA player Skylar Diggins.

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Of course, it was the Cano grab that made headlines and marked the new agency’s debut. But the question remains: Is this the start of a formidable new sports representation empire?

For now, Carter has scooped up some huge names, but the agency is mostly unproven in actually signing deals (since switching to Roc, Cano did snag a new endorsement deal with Pepsi (PEP)). And Carter landed Cano in partnership with CAA, a more established agency with a deep and diverse client list. The specifics of that partnership are not entirely clear, but Roc Nation confirms that it will continue. CAA Baseball co-head Brodie Van Wagenen helped set up the joint venture; it appears the agencies will work together with certain clients, sharing duties.

Carter has shown that he has the ability to woo megastars away from their more traditional agents, but that surprises no one. The initial criticism many are quick to make is that Carter will be a figurehead and the agency amounts to a vanity project in which he wouldn’t participate day-to-day. But this summer, Carter became certified to represent MLB and NBA players, which contradicts that expectation. He also divested his small ownership stake in the Brooklyn Nets so that he could become an agent.

All indications suggest Carter is very serious about this new job. NFL agent certification is likely to follow, but for now, he doesn’t need it: Kim Miale, one of Roc Nation’s four full-time agents, is Geno Smith’s new agent. (And talk about care and attention: For now, he’s her only client.) As for Carter, Roc Nation spokesperson Ron Berkowitz tells Fortune, “He will be involved in all aspects” of client relationships. Still, it’s a stretch to imagine him sitting down at the negotiating table.

Roc Nation Sports “was the natural progression for Jay Z,” says Berkowitz, who adds that the athletes in its current roster of five, “represent exactly the type of client [agents] would want to work with.”

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Jay Z is hardly the usual model of a sports agent. Traditionally, agents are attorneys. Carter doesn’t have a law degree. Agents generally focus on one sport — think Scott Boras in baseball or Drew Rosenhaus in football. Carter is already all over the map. But he has stolen clients from big-name agents like Boras (Cano) and Rob Pelinka (Durant). And boy, does he like to talk about it. This is no friendly, quiet entry into the sports representation world — Carter is trying to kick the gates in. On his newest album, in the song “Crown,” he raps, “Scott Boras, you over, baby” and then, “It’s a new day, hit up K.D.”

All of this might make it hard for team executives to take him seriously, but it might do just the opposite. And sponsors clearly respect Jay Z as a businessperson and brand name. He is a man whose every move gets discussed, and indeed, veteran agents say they are getting a mouthful. “People have asked me, ‘Are you afraid of him?’ I’m not afraid, no,” says a longtime baseball agent who declined to be named. “Odds are a guy who wants to hire Jay Z is not going to want to hire me anyway. Obviously he’s a huge name, and his star power resonates with young athletes, and he’s taking advantage of that.”

That may be a key question for young athletes debating joining Roc Nation Sports: Is Jay Z just a sports enthusiast taking advantage of his celebrity? He may be able to lure established stars in the prime of their careers, but will it work with recruiting young prospects — the traditional way that an agent makes his name? Does he even want to go for those kids? Take hockey as an example — not by any means one of the major sports in terms of contract values or sponsorships, but one Carter has shown interest in. (Seth Jones, repped by CAA, was expected to go first in the NHL draft in June. Leading up to the draft there were reports that Carter wanted to work with CAA on Jones’s marketing. When Jones was ultimately selected fourth, some sports blogs railed that Carter’s rumored involvement weakened teams’ interest in the young star.)

“I’m convinced that a general manager in Toronto is not going to care if a player calls him and says Jay Z is my agent,” suggests Alex Linsky, a rising hockey agent who works with “major junior” players — 16 to 20-year-old top prospects to enter the NHL — in Ontario and Quebec. “I have one player that texted me after every single game to talk about how he did. You can’t convince me Jay-Z will field those texts. Hockey is unique, its culture is different. In the hotbed of Ontario, the agents are there every night. Most of the agents you see almost look like scouts. The ones that look flashy aren’t trusted.”

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Well, of course Carter isn’t going to be at Cape Cod Baseball League games looking for new prospects. He could in fact continue to poach only established stars and build a very nice, respected agency that way. The names he’s shown interest in so far and the deals he’s landed, haven’t been surprising: He already had friendships with Cano and Durant; hockey prospect Jones is the son of Popeye Jones, an assistant coach for the Nets; Pepsi, which Carter connected with Cano, has a deal with his wife, Beyoncé.

But if Carter wants Roc Nation Sports to grow into a deep and multifaceted agency, he’ll need to prove himself more thoroughly as a sports agent. While that could be a challenge, don’t underestimate the ability of the Jay Z empire to woo both veteran and rookie players to the up-and-coming agency. If players and brands buy into it, then in turn, team executives will, too. That means stuffed contracts and, eventually, maybe the next agency empire.

A version of this story also ran at our sister publication SI.com this week as part of its “25 Under 25” package.