Its not like that. There are some methods by which sports broadcast rights are sold. It all depends upon the clauses in the contract-
1. Upon the expiration of a particular broadcast right, the existing broadcaster is asked to renew its rights at predetrmined price for the said period.
OR
2. If the existing broadcaster refuses to renew the rights, there is a competitive bidding & the highest bidder gets the rights.
OR
3. Upon the expiration of the rights, there is a competitive bidding excluding the existing broadcaster but it has the right to match the price offered by the highest bidder. If it refuses, the rights go to the highest bidder.