I wasn't familiar with Clark when I read this article, and I figured he was having the game of his life - he's 24 in A-ball. Then I looked up his stats:

http://www.fangraphs.com/statss.aspx?playerid=paZ07025&position=P

So now I can't understand why he has been brought along what seems to be so slowly. Was he injured last year? He only had 21 starts (23 appearances overall). His numbers are really great. Is the scouting report not-so-great?