Why don't you see Maia taking it down? He took Story and Fitch to the mat. He is huge at 170.
I don't see Maia getting the takedown either. Diaz has a long reach and works a jab well which is rough for someone who has Maia's style of takedowns. Maia doesn't shoot like a wrestler so much as he closes the distance and then drops for it or takes the trip. I think that's a rough TD style for someone with solid boxing.