Remember Roberts came out of nowhere. We are just as likely not to know the next nominee as he or she will be obvious.
Not really. He was being mentioned as a good candidate in the mainstream press (I heard two separate talking head interviews, one on the radio and one on TV) that said he was an ideal candidate, because of his clear intellectual gifts and lack of an attackable track record while on the bench. The conservative media was fixated on more "recognizable", clearly right-wing (and more controversial) candidates, so he wasn't mentioned as much in those circles.