>>338674569
There's a few options they have; they could have a weighted combined score rather than a 'anything over x' rating they have at the moment. That'd be pretty easy. 
I'd rather they focus on render times though. Would be WAY harder though. My suggestion is to have a standard asset included with the SDK, that has a medium level set of meshes, dynamic bones, etc etc, and then compare how that performs to the user's avatar. Differences in frametime - scene frametime could give a reasonably objective rating on how fucking terrible the avatar is. 
It'd be pretty complex and not super reliable, and would also require avatar creators hit a 'generate avatar benchmark' button and then wait 5 minutes. but would be great to add as an optional stat to the performance ratings.
Something to tell TDAs, yes, your 40 mesh 500 bone collider avatar has a performance rating of 900% while that other very poor avatar is 50%.