As a very marketable athlete, one can make inherently more money from endorsements than from a salary paid by a team. Plus, those endorsements can continue even after your playing days are done. Losing endorsements not only hurt at that moment in time, but often other companies will follow the decision of the first and drop the athlete in question as well.
That seems to be where Michael Vick is at at this point in time.
AirTran, which had employed Vick as a pitchman since 2004, decided not to renew his contract when it expired on May 8. AirTran spokesman Tad Hutcheson released this statement about the matter:
"Michael's contract expired May 8, and we advised him then that we would not renew it."
Since 2004, Vick had appeared on five billboards, and some radio commercials. His contract had been renewed twice since it was first signed.
I wasn't able to track down exactly how much his AirTran deal was worth, but it had to have been several million. However, the most costly effect of this decision by AirTran is that Vick's other endorsers could sever their ties with him as well.
Here's a list of some of the other companies he has endorsement deals with:
It will be interesting to see how many of those companies also drop Vick because of his involvement with this dog-fighting investigation. At some point I would imagine that consumers of these products might threaten to boycott unless Vick is removed as a pitchman. It seems that right now may be just the start of a snowball effect involving Vick losing endorsement deals.