I really don't think either of you are really wrong.. Purdy definitely snuck up on Okie State, that's obvious. WVU saw essentially an entire week's worth of game film to get ready for him, and Purdy again showed the first game was not just some fluke. Then as everyone knows, he showed up to play the rest of the year and played like he did the first time he stepped out on the field. He might have surprised teams, but that's their own faults. If they didn't want to believe in the hype and think he's not as good as advertised, they were soon mistaken.
You can be really good and still surprise someone. I thought I knew how good Kyler Murray was before we played him but it really wasn't until he played my team, that I understood how good he really was. Iowa State knew how good Kyler was, but it didn't matter, because he was better. Saying he surprised teams doesn't mean they weren't ready for him or is in anyway demeaning towards Brock. They knew who Brock was and what he could do, yet they still were surprised in truly how good he was after his performances.