He is in a "Before Cumulus" contract more than likely, and considering the previous company that he worked for, 250-350 is probably where he has averaged as a result. Think of the money they weren't able to make early on for years when they had a much smaller signal. In better economic times, he certainly was worth that amount to keep him happy.
And yes, radio stations purposely purposely try to keep them expiring at different times for that reason. Radio station agents have a hard time keeping show's members with the same expiration date sometimes, unless they are hired out of market to a new company. Think about it, the Morning Mess all expired at the same time...lol, and maybe Cumulus want Dauler's wife out of the contract next go around.
If you command that kind of money, then many are forced to take off one or two years off sometimes till you find that one available gig, but then your really not making that kind of money once you average it out. The vacation time that comes with that kind of demand, can make it somewhat worthwhile though.