Yes, ww can burst. But if you’re trained by a warrior or a DH, your defensives feel like paper. Karma is a joke, and is just ignored when you pop it. Fortifying brew seems to do nothing. It’s probably the weakest defensive in the game with its 6 min cd for half the dmg reduction a warrior gets on his 2 min cd. Dampen harm seems to do nothing as well.
And as for the mobility. That used to be a windwalker strength. But now all classes have great mobility. It is no longer an advantage ww has.
Going toe to toe with a fury warrior, I lose every time. They have burst that is easily as good as ww monks, and way better defensives and self healing. They have a stun on half the cd monks have, and they can even get one more in their talent tree.
Same for DH. They have everything monk has, only better. More burst, more self healing. More and better stuns, better defensive cds.
I don’t have statistics on the representation of ww monk in arena at the moment, but I have over 100 games by now, mostly 2v2 and solo shuffle. And in all those games I think Ive seen another ww monk one or two times. People don’t want to play it because its so weak defensively. Can do good damage, but can’t take a hit. Bad kung fu that is.