Yeah, the K/9 thing is a little bit of a red flag. Still, he's a ground ball pitcher, and that's trending in the right direction (2.36 GB/FB this year, after 1.57 and 1.73 in the previous two seasons) and ground ball pitchers can succeed with lower strikeout rates, especially if they have a good defense behind them.
There's enough there that he's really intriguing. I mean, I wouldn't give up a ton for him...but a 23 year old is a 23 year old, and BA had him as a really good prospect a few years ago. Unless the alternative is Greinke (or maybe Sanchez or Jackson), I'm not sure the Cubs are going to be able to do better for a decent price this offseason.