(Karen Warren / AP)

Johnny Manziel, the star Texas A&M quarterback, became an instant sports celebrity last season after handing the Alabama Crimson Tide its one defeat in a national championship season and becoming the first freshman in the history of college football to win the Heisman Trophy.

Eight months later, his fame is increasingly tied not just to his on-field athletic prowess but to his off-season antics: shoving a grad assistant coach in practice, sending negative or otherwise controversial tweets, his early departure from the Manning football camp, and a guilty plea in a bar fight that occurred a year earlier. Now, new allegations add more serious charges for the 20-year-old football star. ESPN.com reported on Sunday that the NCAA is investigating whether Manziel was paid for signing hundreds of autographs.

The troubles of Johnny Football--as the quarterback phenom is known--have sparked a debate in college sports: Are these the antics of a reckless athlete who's seizing the spotlight and letting fame go to his head? Or are they simply the actions of a 20-year-old kid (at least, before the autograph allegations) that have been magnified under the glare of what is arguably college sport's highest honor?

The Heisman Trust's mission each year is to recognize "the outstanding college football player whose performance best exhibits the pursuit of excellence with integrity," its Web site reads. "Winners epitomize great ability combined with diligence, perseverance, and hard work." In other words, the Heisman Trophy is awarded to the sport's greatest athlete each year, but one who also emulates off-field leadership.

As a result, the reigning Heisman Trophy winner is simply held to a different standard. That responsibility is difficult enough for a junior or senior who's spent a few years in the media spotlight and is about to head off to the pros. It's even harder for a 19- or 20-year-old kid who's had little exposure to the media and must now navigate the fishbowl of fame that comes with such an honor. As Texas A&M's athletic director reportedly told Manziel's parents after he won the Heisman, "He's no longer a freshman, and he's no longer a sophomore, junior or senior. He is a 'Heisman.'”

How different players react to such scrutiny--Tim Tebow, the Heisman's first sophomore recipient, appears to have handled it just fine--is the result of an array of factors that range from personality to upbringing to media buzz to support from parents, professionals and college leaders. How much of that backing Manziel is getting seems to be under debate. A&M officials have stressed their supportive role in helping their quarterback transition to post-Heisman life, while Manziel's family, at least in a recent ESPN feature called "The Trouble with Johnny," seems to question it.

I'm not saying the Heisman shouldn't ever go to freshmen. And I'm not at all saying Manziel shouldn't be held accountable for his actions--he needs to step up and embrace the responsibility of being a Heisman winner. That especially goes for any alleged NCAA violations. However much the NCAA's amateur rules may be antiquated, they are the rules and everyone must play by them.

But as younger and younger players win this prestigious award, everyone involved in the sport will need to remember one thing: For all the good the trophy does in recognizing athletes, it also brings with it a level of scrutiny and glare that makes it harder for these young stars to really grow into the leaders with "excellence and integrity" that the football world already deems them to be.

Jena McGregor is a columnist for On Leadership.

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