Posted By:
fkwWhy would you think it is a proof? Does the card have a blank back? Or does it have printers cross hash marks on the edges?
I have a blank back card that some might call a E90-1 proof, but some of the players in E90-1 have the same fronts as E92, E101, E102 etc. so its impossible to pinpoint the exact set.

SGC could have chose to slab this as a E90-1 or E101 Proof too. I wish they would have said it was a E90-1 since the McLean in that set is a tough one