Why isn't jake shields given a shot in an against gsp?

I think he has a shot if he can make it a wrestling match and keep the fight on the mat and dominate GSP that way and I think that is what he is going to try and do. While he has added some power and muscle to his frame and hits and kicks with more authority GSP still has a huge edge in that department. Shield's ability to take a punch I would call only average and so standing up with GSP is probably not the way to go.