When we look at endorsements in sports is just a portion of whats out there. Companies has been using celeberties for as long as there been television. It was not until the 80's athelets started to get some of the action. Players like Michael Jordan was a poster child for Nike who opened the door for athletes to be used to promote their product. Nike also used Tiger Woods to get started in  the golf world. Here is an articile that explains it.

Branding and Celebrity Endorsements

Nike is known around the world for being one of the most iconic brands. It was recently ranked as the world’s 31st most valuable brand in terms of its brand value – USD10.8 billion – by the annual Business Week’s global top 100 brand survey. In spite of many market maneuvers (such as the recent merger between Adidas and Reebok), Nike has remained the leader in its category. Nike is also very well known for another aspect and that is its consistent use of celebrities to endorse the brand. In fact one of the most successful collaborations between a brand and a celebrity is that of Nike and Michael Jordan. So successful was the collaboration that Nike and Jordan launched a new brand variant called the Air Jordan line of sport shoes. Nike pulled off a very similar coup in the sports industry when it joined forces with the ace golfer Tiger Woods to enter the golf category with its apparel, equipment and accessories. Nike had no experience in golf before. Moreover, golf being a very elite game, it was generally considered that a brand like Nike would not be very successful. This might have probably been true had Nike chosen the traditional path to building its equity in the golfing arena. But Nike chose to associate with the best golfer in the world and have him endorse the brand. As is known today, Nike has emerged highly successful in golf.
This channel now being used by many brands around the world raises some crucial questions about ways brands are built and also about the impact such collaborations have on branding. Is associating with a leading celebrity the easiest way to build a brand? Should celebrity endorsement be the principal channel of brand communications? How can brands decide on potential brand endorsers? What are the advantages and disadvantages of such endorsements? Is celebrity endorsement always beneficial to the brand? How does a celebrity enhances a brand image? Answers to these and many other related questions are the content of this article.

Joe Namath & Beautymist pantyhose
  OJ Simpson & Hertz Perhaps the worst ever celebrity endorsement was car rental company Hertz's choice for a spokesman: OJ Simpson. Endorsements can be good and bad. We never know what will happen with athletes, so those who take a chance know that they are taking a risk but as stated in the article that the risk is far  greater than not to.