I have the same problem, I am 100% stock.
What I noticed is if I reboot my phone the battery will behave correctly for a couple of days then suddenly Android OS will take over and drain it
With Android OS drain I get
3% drain per hour with no use (Wifi on every 20 min to sync)
10% drain overnight (7/8 hours with wifi on every 1 hr)
sometimes I have like 30 mins screen on time and the Android OS CPU total and Keep Awake over 3 hours (lol)
Normally, I get barely 1% drain per hr during the day if not using it and almost no drain at night
I already disabled NewsStand and I am about to try to disable Google+ even though I like the Auto-Backup feature.