Sketch cards - Who actually draws them?

Last month I approached a local friend of mine who I knew was a great artist to draw and donate something to a charity auction I'm overseeing next week.  He recently told me that he had finished the piece and also asked me if I still collected trading cards.  I told him that I've backed off the cards a little, but yes, I was still collecting.  He then proceeded to tell me that Topps had contacted him about supplying several sketch cards for an upcoming Topps UFC set of cards!  Since being told the news, I haven't actually had the chance to ask him how all of that came about.  I figured Topps used famous artists or whatever.  Guess not.  Here is a test sketch he just finished of Hershel Walker who went 2-0.  Can't wait to see the final product once he's given his actual assignment by Topps.