Battery calibration is unnecessary. I use GSam Battery Monitor to keep all my apps in check, see which is using the most battery. Facebook and Currents can be common culprits for background processes that kill your phone. Also, you might want to install CPU Spy to make sure the processor is going into deep sleep. Sometimes an app will try to keep the phone awake all the time, which will kill the battery. Install, then let the phone sit screen off unplugged for a minute, then refresh the app. Make sure that Deep Sleep shows up in the list of processor states.
The other thing I would recommend is just a restart if you haven't tried it. If nothing seems to be out of the ordinary and you are still getting poorer battery life, I would call Google and try to get a replacement, there could be something wrong with your device.