What are you basing his athleticism on?
He's slow and plodding.
Chael is much faster.
Grappling strength =/= athleticism.
It's about as funny as the claims he will submit Silva based on his two purple belt submissions over Jesse Bongfeltd and Tom Lawlor.
I'm not saying he's the most agile MW but he's very fast for his size and his coordination and movements is a testament to his athleticism. I'm also not saying he will submit Silva but I find it very unlikely he'll get submitted either.
I love GSP but Weidman and Bones are the only two non HW's on the planet I see beating Silva.