It's really not as crazy as it sounds. When you're investing in stocks, particularly in adolescent companies, you're invested in their long-term potential in most cases. Just as an injury can wreck the career of an NFL running back and leave him worthless in this scenario, you have your Enrons of the world. Also, think about the fiasco with the BP oil spill a few years ago. A lot of people bailed on the stock because they thought the company would never regain the ground it had lost. Others decided to stay in or "buy-low" once others had bailed, and they were rewarded when it rebounded. I imagine the same type of mechanics apply here. Let's look at a hypothetical:
Imagine Adrian Peterson signed a contract with this company in training camp prior to his first season. Coming into the league, some people were very high on him, and others were skeptical because of injury history, running style, whatever. Let's say these circumstances set a "share" of AP at $30. Fast-forward four years, and his perceived value has been confirmed, he is widely considered the best RB in the league, and has signed multiple lucrative endorsement contracts. His share price has skyrocketed to $90 at this point, and those that got in at the ground floor have realized a good deal of profit. Then comes 2011. He's riding high until he is placed on injured reserve for tearing his ACL and MCL, and a great deal of investors decide to jump ship before his stock falls too low. Will he ever come back the same player? Will he lose his endorsements? As a result of these fears, his share price plummets to $60 a share. Those that have stuck with him since the beginning and those that buy in at this level believe he will rebound, even if it is a risky venture. The next year their faith is rewarded, as AP bursts back onto the scene as good as ever, and his stock price jumps up to a new high of $95 by the end of the 2012 season.
I imagine that's how it would work. You're basically using knowledge you'd normally apply to some aspects of FF to make financial decisions. You think that nobody WR on the Giants whose stock is $5 a share has potential? You invest on the ground floor, and when said Victor Cruz goes off and signs a huge contract down the road you make off like a bandit. It's a pretty interesting concept, and I'll be following it closely.