I’m assuming you’re referring to WLNY, now WNYW. Thing is, you can’t really compare the two. WLNY was a small LI station that was allegedly bought in exchange for a golf membership. There were never serious investments made, and when CBS bought the station, they actually cut WLNY’s news department entirely. Meanwhile, KCAL is a station that built a solid reputation for itself in the 90s, and carved out a niche audience by doing news in prime time. It also helps that they hired away Jerry Dunphy to give them credibility on day 1. By the time CBS bought them, they had been well-established for a while. I’m not an expert on the market, but it seems to have gotten to the point that KCAL has a better reputation than KCBS, even though they’re under the same umbrella.
And besides, if your stations are going to air local news from 4-11am, why split it between KCBS and KCAL and force viewers to change channels at 7am? KCBS gets to show live national news (which no other station does), while KCAL gets better programming in the morning than it has now. Both stations can concentrate on their specific audiences. It’s better than showing a newscast that pulls a whopping 0.0, which in turn hurts the national morning show.