Important things like Mp5 and Spirit are only really needed in the long fights of pve not in the short fights in pvp.  So that's what usually gets cut when you need to swap in resilience on pvp gear.

First week ZA came out I went there with my druid tank who's geared enough to MT Gruul and Mag, and everyone else likewise, and it took twice as long to burn through the health of one boss versus a kara boss.