Well, apparently Jon and Tyrion are there to represent the 50% of the audience that didn't see it coming!
I actually find Tyrion's arc to be quite interesting. He's gone from one of the most devious and clever characters to one of the most naive and foolish in direct relation to him becoming more loyal and humane (which I guess most would see as positive character traits). Then again, it could just the volume of wine he's drinking.
Yeah, Tyrion was my favorite character, but has been such a disappointment in the past few seasons now.
Even his own actor made fun of how dumb Tyrion is now.