As a Phillies fan, I saw him pitch in a number of games late last season. He walked way too many guys and struck way out too few. For that reason, I wasn't real high on him entering the season.
Well, he seems to have learned from his mistakes. He seems to be a much smarter pitcher this year.
He does get rattled a little easier than you'd hope -- in fact, he lost his composure a bit in yesterday's game v. Montreal. He was able to work through it yesterday, but young pitchers have to learn to deal w/ bad calls, errors, etc. He's still learning.
He's got great stuff, though. He's definitely worth a pickup in keeper leagues and in 10-team non-keeper leagues.
Everything you know is wrong.