Yes his top-end potential is limited by his team not being that good and he isn't a Peavy K-artist. I'd pick him up if I needed some low-ratio innings and had someone to drop, but he's much better in HTH than in roto with IP maxes. The number of wins and ks per inning he pitches won't be enough to make him a very good pitcher in roto - basically a 2-cat guy. And that's if he doesn't blow up and start pitching closer to his career numbers.
That said, I have him in my 5x5 HTH and am liking him so far. I'm pitching him based on matchups and he hasn't burned me yet*.
*Note: I just jinxed him. His next start will now be a 12 ER, 1.2 IP outing. Sorry.