After signing New York Yankees second baseman Robinson Cano as his first client, Jay-Z – who made the bulk of his half-billion-dollar fortune in the music industry – has targeted players from other sports: Thunder star Kevin Durant, WNBA rookie Skylar Diggins, and Jets quarterback Geno Smith. 

Jay-Z also is known to be interested in signing another Cuban baseball player, Oakland A's outfielder Yoenis Cespedes, according to a source. Next week, Cespedes will be in New York, Jay-Z's hometown, for the Home Run Derby, and Puig could be as well if he wins the Final Vote for the last slot on the National League All-Star team. 

Jay-Z

 In the song "Crown" on his recently released album, Magna Carta Holy Grail, Jay-Z took a shot at prominent baseball agent Scott Boras, rapping: "Scott Boras, you over, baby. Robinson Cano, you coming with me." While Boras declined to fire back, agents around baseball have questioned the wisdom in signing with a fledgling agency run by somebody with no experience negotiating sports contracts. Roc Nation Sports has partnered on the baseball side with Creative Artists Agency.

Is Jay-Z doing this for love or for money? Or for both?

I like Jay-Z so much I believe he does everything for love primarily.  

Is he going to bother to learn how to negotiate sports contracts before he puts these athletes' careers on the line?

<Some analysts said that they expected that Jay-Z would add a sprinkling of celebrity dust to Creative Artists’ sports division, but that he would do little more than bring athletes to the table.

“This is really an arrangement with C.A.A.,” said Jordan Kobritz, the chairman of the sport management department at SUNY Cortland and a former owner of a minor league baseball team in Daytona, Fla. “Jay-Z is part of their recruiting arm because he has access, and is a public entity, and New York is his cradle.”>

http://www.nytimes.com/2013/04/03/sports/new-jay-z-lyrics-for-athletes-please-let-me-represent-you.html?pagewanted=all&_r=0

I'm surprised more celebrities don't try to use their charisma for things like this.