OAK has a lot of potential and I think they could easily add 5-10 destinations 2-3x a week and fill the flights on a regular basis. For some reason it hasn't been a focus. In most cases OAK has the least amount of flying even compared to Myrtle Beach. My guess for why it's a revolving door... If you're a Bay Area based pilot you'd probably be better off waiting for United, and for some people WN/Virgin Alaska might be a better fit.