What makes you think that? A lot of people had said The Wave was completely dead two years ago. Now it's a Top 5 station.
I'm really just stating the obvious. The station has no growth at the moment. They're currently declining.
When you have a solid product and are making a ton of money from it, you don't feel compelled to change things. That's KROQ. They made a ton of money with the same DJs, same morning show, same music, same amount of commercials, etc.
And it's tough to shed your roots and try to appeal to a new audience when your legacy is what's holding you together. Since revenues/profits are still important, it's tough for KROQ to go ahead and try something new.
Although KYSR and KROQ's playlists are virtually identical at this point, I think KYSR's success is based on what they did different from KROQ over the past few years:
1. KYSR played less recurrents (i.e. '90s gold titles) than KROQ.
2. KYSR found a morning show that is competitive to Kevin and Bean.
3. Rebranding to ALT 98.7 gave the station more identity with listeners.
Growing up, I would listen to KROQ religiously. Not just because I loved the alternative rock genre, but because the mix of music was relatively eclectic and different. Maybe that's a good way to rebuild audience.