Review on Protective Carrying Case for Xbox Controller: YSAGi Travel Edition (Black) by Jeanette Lee

Looks like it will eventually damage analog sticks. Possible cause of drift. It's not deep enough. The sticks are higher than the body and won't close completely unless you force them. Pressure on the sticks during transport is a risk, so no backpacks or piles of books like in the pictures. You may be squeezing the sticks incorrectly.