He was not alone. Everyone on the right thought Roberts was the ultimate pick. Wow were we wrong!
I think everyone on the right believed that W would appoint true strict constructionist to the court, as he promised, and they trusted him during the Roberts appointment, a candidate most knew little about.
Then with the Harriet Myers nomination, people began to trust W a lot less, and that one was ended by an uproar from the right and Alito was nominated, a judge with a track record that could be reviewed.