I am just still learning about this. Apparently my piriformis is trying to do some of the work of my glute max. i was able to tell my left ehmmm cheek wasn't contracting on demand, and it seemed to be weak. my physio figured out that my piriformis was over doing it.

i should also mention i have a scoliosis in my low spine along with shearing between L3-L5 which doesn't help things either.