Well according to them it's supposed to help with burst, I'm absolutely not convinced about that. All it does is to be even more beneficial for PvE geared people making the gap even in rated PvP far smaller than before.
In World PvP the 522 (soon 530) PvE gear was already superior, according to them however the "higher dmg" and "higher healing" was supposed to offset that (guess what, it really didn't, the difference is way to massive). So where does that leave us after the most recent change? Afterall PvP geared people just lost about 1/3 of their bonus dmg and healing.
In Rated PvP this is going to make some PvE pieces especially for classes who go for resilience far more beneficial seeing how they often have more sockets and thus allow for more gems and in some other cases this will make some T-pieces for set bonuses an even better/an alternative.
All in all MoP PvP is going into a direction I absolutely hate. I'm playing since TBC, I've always been a PvP main/only player and ofc I loathed seeing some PvE pieces in PvP. But making them flat out better for World PvP and a real alternative/often superior in ranked PvP gets me to the point for the first time where I really don't want to play this game anymore.