NFL players, watch your millions, pro warns

What's at stake for NFL draft
What's at stake for NFL draft

It's that time of year again—when young college football stars find out if and where they'll wind up in the National Football League and what their payday will be. But if they aren't careful, those multi-million dollar paychecks won't get them very far.

"Let's just hope that this year's rookie class understands the reality behind the numbers and takes measures to save and invest their earnings, keeping in mind that, on average, their career will only last shortly over three years," said Jack Brewer, a former NFL player who now runs The Brewer Group, an investment company that caters to athletes.

The NFL draft kicked off Thursday night in New York, and Brewer estimates the No. 1 draft pick (which ended up being the University of South Carolina's Jadeveon Clowney) could see a contract in the range of $25-28 million. While that's big money, he said it dwarfs the paydays seen in the past—like the $60 million contract the No. 1 pick, David Carr, saw in 2002.

Jadeveon Clowney of the South Carolina Gamecocks with NFL Commissioner Roger Goodell after he was picked #1 overall by the Houston Texans during the first round of the 2014 NFL Draft, May 8, 2014 in New York City.
Getty Images

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"There have been drastic changes in the way rookies are compensated in the National Football League" thanks to the 10-year collective bargaining agreement that ended the NFL lockout in 2011, Brewer told CNBC's "Power Lunch."

"A lot of it I think is for the better. Some of the lower round guys get more guaranteed money but at the same time the National Football League is making a pretty penny."

Former Tennessee Titans quarterback Vince Young learned the hard way how quickly a multi-million dollar paycheck can disappear. He filed for bankruptcy protection earlier this year but has since settled his debt and asked for the Chapter 11 case to be dismissed, according to the Houston Chronicle. He's once again playing ball, signing a one-year deal with the Cleveland Browns.

Brewer's advice to players—invest carefully and negotiate better.

"The players ... have to negotiate better business contracts," he said. "From a business perspective, the owners are winning."

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By CNBC's Michelle Fox. CNBC's Jennet Chin contributed to this report.