I had keep awake times in Android OS (the specific battery entry not overall Lollipop) that were way too high. I know others have experienced this, as well.
I don't think this is a one-thing-fixes-all-our-problems fix. In my case, it was Fenix that was apparently working much harder than it had to in the background. I uninstalled that app and my keep awake times in Android OS dropped exponentially. My battery life overall now seems much more reasonable. I was getting great SoT of 5 hours or so, but only 11 hours of total battery life. It was as if keeping the screen on *saved* battery!
So, it may require some trial and error and guesswork to figure out this keep awake issue for somebody else, but look for apps that sync or look for updated messages first. Assuming you have already taken care of the Google apps that do this, the list should be somewhat small (i.e. Facebook, Twitter apps, Instagram, etc.).