Chiang has about solid-average batspeed and he has to cheat on high velocity fastballs making him very succeptable to breaking balls.  He runs into mistake fastballs well, but on well spotted fastballs with good zip he has trouble getting the fat part of the bat on the ball.  Especially running away from him as he doesn't cover the outer third well with his swing since his hips open up early and the head of the bat is out in front of the ball.  Chiang doesn't use his hands well on balls away.  I have seen him hit 5 home runs this year and 4 of them were on 88-90 MPH fastballs in the exact same spot.  Just about at the thighs and right down the middle.  The other home run was on a hanging slider on the inside third that he turned on.  The power has been pretty good and he's learned to muscle up balls in his wheel house.  But, that hitting zone is limited to middle/in on average velocity stuff.  He just has ok bat control as well and has a tough time spoiling pitches with two strikes. 

Chiang's made improvements, especially with picking up secondary offerings and not consistently bailing against anything with break like he did at the start of the 2010 season in Portland.  He's had a good season thus far and has been a pleasant surprise.  I just don't see these type of stats translating to the major league level given the skills I have seen.  And, when you throw in his defense is fringe-average in the outfield right now he's going to have to hit like this season in and season out to be a major league regular.  See him more as a AAA guy with the potential to be a 4th/5th outfielder type in the right situation