It is really important in these conversations to consider two things:
Generally speaking, BJJ, Judo, Sambo, and Wrestling when applied to MMA are basically just starting points. At the end of the day there is a finite number of ways two human bodies can interact, and an excellent double in wrestling, pre 2010 judo, or BJJ still relies on the same mechanics and variables. Generally a style in this context claiming total ownership of anything gets a little suspect, since ultimately mma grappling is its own beast and everyone needs to make big adjustments to their grappling games when making that transition.
As mentioned elsewhere Chael has the perspective of an elite Olympic style wrestler. In a pure greco/folk/freestyle match, Maia doesn't have elite wrestling. Hell GSP despite all the hype in 08 about him maybe making a run for the Canadian Olympic team, didn't have elite wrestling by that standard, and his MMA wrestling was/is amazing. Within the context that Maia applies it, its does what it needs to do, and is thus quality.