-Ya, something is funky... I ride very bumpy, rocky terrain and bash the crap out of my 575, outside of initial adjustment I have never had a single adjustment or der. issue.
BTW I'm runnning X9 rear with jagwire. On my bike I have a full housing on the rear cable. The cable runs along the downtube on the non drive side then crosses over to the drive side at the bottom bracket. The ONLY cable that goes UNDER the BB is my front der.
I know there are probably different cable routes but if you have a full housing and it runs UNDER the BB that sounds wrong. There is almost no way my rear cable could be hit by a log or rock, it would have to bash the chainring first.
Check out the cable routing link on Yeti's website and compare it with yours.