Well at least you're farming them from the right place, which is good to check before you start. :P
And consider yourself lucky so far, I didn't see T2 legs for months while I cleared MC every week. Had all the rest of the set (not to mention a completed Sulfuras), the legs just eluded me. But thankfully I have them now.
And yeah, the drop rate is somewhere around 10-20%, since two T2 legs will drop from Rag. Wowhead says 18%. Keep at it, you'll get 'em eventually. And at least MC is easy to solo.