The irony in this question is palpable, since "The Wolf" itself was a replacement for a popular "adult hits" format known as KMAX in early 2007(*).
The simplest answer is this: terrestrial radio shares many of the revenue generation problems that newspapers have, in large part due to the Internet. Because of this, station management and owner(s) are left constantly chasing the hot format of the moment… As each radio market rebalances over time, the numbers start to look good for jumping ship on whatever the station is currently running, and going with something new. This isn't true of every station necessarily, so you're left with stalwarts like KFOG and the like… But for a station like 95.7, which has already swapped formats and received an initial ratings bump, doing so again doesn't seem like that bad an idea.
Plus, let's face it – sports radio is primarily focused on American Men's sports, and SF recently brought home a World Series championship… Between that and the still-fresh Barry Bonds case, you have a lot of sports fans chomping at the bit to give their two cents on air. There's also a possibility that someone is seeing dollar signs in the America's Cup, which isn't that far off…
So, long story short, the answer is: the radio business is about making money from advertising. Your favored format, country music, was simply not as lucrative in the eyes of station management compared to sports talk radio.
(*) For a full history of the many format swaps of the identity-confused station sitting at 95.7 on your radio dial, try the excellent Wikipedia entry here: