Here's a little sports/business-marketing 101:
If you take less money upfront to give your team a chance to win multiple championships, should your team actually win....you make all that money back and then some, on the backend via sponsorships, endorsements, etc.
Yes, it's a gamble, but corporations would much rather pay a championship winning athlete than an athlete who ain't winning chips.
Not saying you need to be a champion to be in commercials, but I am saying the bread is much better if you are.