I would think that ALL stations in SoCal would love to be in first place (even KJLH)...the problem is, it's not holding down KROQ. Why would any station who flipped formats just immediately have to have the urge to be in competion with a station that doesn't exist?
You're probably right about the first point... just that with the composition of the LA market hard to see any rock station making it to the top if the audience is fragmented by two stations. That doesn't mean there's not the niche for them though. As far as the second point, if memory serves me right KROQ used to often be in the top 5 sharewise, not really there anymore. Although KYSR has slid some lately...
The comparison with Star is that 98.7 is doing better than they used to on the Star format... not that they're competing against a station that doesn't exist... they were star!