Usually I try to be indifferent to all patchnotes and announced changes until they actually occur. The past has shown, that one can avoid many unpleasant moments doing so. Then (after realising, that neither DD nor Prot Tier 16 Setboni were nerfed) I stumbled over Riposte:
Riposte (New) When you dodge or parry any attack, you gain 50% of your Parry and Dodge as additional Critical Strike for 20 sec. Warrior - Protection Spec.
Considering, that, additionally to our critical blocks, shieldbash and devestate will be able to enrage us, I think that new ability is pretty sweet. I checked my current stats and I roughly have 32 % avoidance (gearscore 532), which will transfer into 16% crit + 5% basecrit + 5% critbuff - 3% bossmalus = 23% crit or 26% crit against trash/adds. The duration of 20 seconds will quite surely enable us to maintain the buff as long as we keep bashing stuff.
This has some nice side effects. Recklessness becomes a pseudo-cooldown, granting us 30% crit, pushing us over 50%, thus, flooding us with rage, i.e. mitigation. Furthermore it will push our damage and threat: Devestate is our FILLER and Shieldbash can procc from Sword and Board.
The big question is what we will gem in 5.4, assuming those abilities won´t be changed. While I´m being really bad at math, I can think of two options. Both favor hit/exp over all, for them being our most certain rage-generators. After that, we will have to decide if we favor crit or mastery. Crit will potentially grant us more rage, thus, more mitigation, while mastery will boost blockchance as well as critical blockchance, with critical blocks also granting us enrage.
As I mentioned, I´m bad at math, but currently I feel like having roughly every fourth strike a crit is already okay. With gemming one might reach 30% crit or more, but I wonder if that is worth sacrificing mastery to a great extent. Perhaps someone wishes to throw some numbers around?
Edit: Just wanted to add, that every tank´s taunt ability gets improved. Taunt will grant 200% threat in the following 3 seconds. Will be nice in early stages when you have to out-threat bursting enhancers and mages with mirror images. Oh, Monks don´t get that buff btw. Some lulz was had.
Edit 2: Deathknights get Riposte as well. Earned, i guess. They have been in a bad spot lately as well.