The thing that makes Diaz an interesting opponent for GSP's safe style is the fact that there's no real safe place to fight Diaz. Sure, GSP may use his wrestling, which has been a weak point for Diaz, but Diaz has a great ground game, so there is still risk. IMO, I think Diaz has pretty comparable stand-up and Diaz is not afraid to get hit and can take a punch. If Diaz starts landing the jabs on GSP, he way very well take this fight. We all know GSP does not like and it not used to getting punched.
I think Diaz has a great chance at beating GSP. I think Diaz is a handful for many reasons and just the guy to make GSP fight if nothing else.