Sorry for the double-quote, happens when real life stuff trumps gaming.
For the first, I didn't mean that Pulverize right now is meant to replace Mangle, I stated that at some point in an earlier alpha build it appears Pulverize was probably toyed with as replacing Mangle. In the later builds, which we've seen currently, it gives the appearance of being reverted back to a separate ability not meant to replace Mangle while still having some residual affects from being meant to replace Mangle. Happens quite often in coding when you alter some specific code back and forth while working with different versions of the same thing. I expect some change in the basic conditions and resulting effects of Pulverize in future builds.
With respect to Thrash, it could go either way with haste. I doubt having too much rage is of much concern, as we'd deal with it in a similar way as we do now: rage-dump via Maul/FR or just let rage cap. Plus, I don't think any Guardian ever
really complains about having too much rage, as having too little or not enough at the right time is much, much worse. If Thrash DoT's eventually become affected by haste, I think the simple solution for rage generation from the extra tick would be just dividing 2 rage by the fraction of a tick we receive. I'm pretty sure it'd always award at least 1 rage or a maximum of 2 rage, but that's hardly anything to min/max over.
It'd definitely make sense if their goal is to have haste push rage generation from all aspects "faster" across the board. How good or bad haste turns out will be at the mercy of scaling. As long as we can generate good threat from Thrash to where another tank doesn't just one-and-done beat our AoE threat even with a decent lead, I think we'll be at a good starting point!