netflix can still be in the background running. maybe uninstall it for a bit and see if you notice any changes?
ive not noticed any battery decrease after any update and i am stock unrooted also.
i would look at your screen brightness, and turn off any RF services (BT, WIFI, 4G) if you dont need them.
but if you noticed decreased runtime with a hard reset and no apps installed, i would look at possibly a faulty battery. could also be something physically wrong with the handset. have you taken it to sprint repair? if not, this may be a good time to do so.
OT but you are an EMT? in a previous life i used to be a firefighter and would also work on the ambulance in that county. 9 years... good times..