There's been a lot of news about class balance lately. Not only did the devs do a live Q&A recently (here are the important -- that is, the warrior-related -- answers), but they've also been commenting and clarifying on the forums. There's a lot of interesting stuff to consider, and so here we go considering it and the ramifications it all brings or will bring. Here's just one example.
Right now, mastery is decent for arms, terrible for fury, and very solid for protection warriors. Apparently, it's too good for protection right now. While both paladins and warriors use block somewhat differently (Critical Block and Shield Block work together very well), it's pretty easy for either to get pretty high block. Since the active mitigation tanking model didn't manifest in time for patch 4.3, it seems likely that the mastery and block issue will be addressed when that rolls out. It's frustrating, but right now all we can do is wait and see.