According to recent rumors, MLB scouts have been watching 30 year old (turns 31 in July) Korean right-handed reliever Oh Seung-hwan. The Samsung Lions' closer has a career ERA of 1.64, 2.18 kwERA, and 2.20 FIP in the Korea Baseball Organization.
Samsung's park plays neutral (not my park factors) in the KBO, so we don't have to worry about that. According to my FIP WAA measure, he was worth 1.75 wins above an average pitcher in 2012, which was better than Scott Proctor (who has since retired after struggling in AAA in 2013) and Yoon Suk-Min, a starting pitcher who is represented by Scott Boras and rumored to be coming to the MLB some time soon. So statistically, he looks like the real deal comparatively, striking out 33 % of Korean hitters in his career.
Physically, he isn't real tall, but has a pretty broad frame, looking somewhat big, but not hefty or overweight. In fact, he is listed at just 5.84 feet (about 5'10) and just over 200 pounds. Despite this, he seems to get good plane on the ball, with some downward movement on some of his fastball.
According to Naver, Oh features a 90-97 MPH fastball, with a slider he throws 80-89 MPH, and an occasional curve at 71-79 MPH. When high, the fastball is pretty straight (which seems to be his preferred location) and the general average I saw was about 93 MPH. It seems to me that he throws a separate fastball and sinker, and features one or the other depending on the outing (at least it seemed this way based on video). I am not real impressed with his slider movement wise, as it does get glove side, but doesn't break sharply. It bites more downwardly than sideways, and does a good job of changing eye levels at least. His curveball doesn't have great vertical depth, and is a little slow, but he gets it to move glove side.
The Naver scouting reports also say he throws an occasional two-seam fastball to lefties, which sounds like a cutter to me. I never saw one in the videos I watched of Oh. They question his ability to use a breaking ball other than a slider, which may lead to platoon splits in the MLB (so far this year in the KBO, he has struck out 11 lefties and walked 0, for whatever small sample size KBO splits are worth). Even though the scouting report doesn't mention it, I also saw him throw some arm-side changes at 86-87 MPH. It isn't a big part of his repertoire and he doesn't seem to have much control over it.
His heat maps suggest that he likes to keep the ball arm side for the most part. Mechanically he is relatively simple (though he has a high leg kick), but perhaps jerks the ball a little bit too much with a violent over the top motion. While walks have never been a problem for Oh in his career, in videos I saw him struggle with command, it was because he was missing glove side by jerking the ball too much. His stride is somewhat normal, but the delivery is really quick (especially with runners on base, as he ditches the leg kick). His landing point isn't always consistent or smooth. At the time of release point, his back seems relatively upright, but is leaning to the left a bit.
The elbow (2010 and college) and shoulder (2009) injuries are going to rightfully scare some teams. Though, since he has been a reliever for the entirety of his KBO career (as far as I can see), it is doubtful that he has had to endure the high pitch counts that have become somewhat notorious in the East Asia. At 31 years of age at the time of signing, he will be on the "downslope" of his career, but he has a track record of professional dominance, a big league average to plus fastball, a useable breaking ball and mechanics that shouldn't bring up any major control problems. He looks like a big league reliever to me, one that can at least fit in a MLB bullpen and get a lot of right-handed hitters out.