Seung Hwan Oh riding fourseamer to early MLB success

Over the offseason, general manager John Mozeliak and the Cardinals agreed to an international free agent contract with Seung Hwan Oh, a 33-year-old right-handed relief pitcher who had earned the nicknames of "The Final Boss" and "Stone Buddha" from his time spent as a closer in both the Korean and Japanese professional baseball leagues. Despite these telling nicknames, being skeptical about what Oh could provide to the Cardinals was not necessarily an unreasonable stance to take. There was never a guarantee that a 33-year-old pitching in the major leagues for the first time would be able to experience consistent success. Yet, through 59 team games, Oh leads the Cardinals' bullpen in appearances, innings pitched, strikeout rate (K%), ERA, FIP, and fWAR.

2016 Statistics

PitchF/x Basics (Via BrooksBaseball.net)

Remember: Regarding horizontal movement in right-handed pitchers, a negative value means arm-side movement, whereas a positive value means glove-side movement.

As advertised, Oh's primary weapons are his fourseamer and slider, and both have been extremely effective pitches through his first 30 MLB appearances. Averaging ~93 MPH, you would not necessarily think a fourseamer would be such a dominant pitch for an MLB reliever, but that is exactly what it has been thus far for Oh -- and it leads the entire Cardinals' pitching staff (starters included) in producing swings and misses. Regarding the slider, it is clearly of the wipe-out variety considering it has produced whiffs on 50.72% of swings.

What is most frightening for opposing hitters is the fact that Oh also throws an above-average changeup that, too, induces a lot of swings and misses (for perspective, Trevor Rosenthal's changeup induces whiffs on 39.04% of swings). That being said, the changeup is a pitch he does not even utilize fully, but frankly, this is largely because he has not necessarily needed it just yet. His fastball-slider combination has worked quite well, but it is reassuring to know he has another weapon in his repertoire as hitters begin adjust to his top two pitches. Only the very best relief pitchers possess three above-average pitches that they are able to throw in virtually any count. Oh appears to be one of them.

Fourseamer Location (Via BaseballSavant.mlb.com)

To put it bluntly, Oh has been the anti-Michael Wacha up to this point. While we regularly cringe any time Wacha loses his fourseamer up in the zone, Oh has produced much of his bullpen-leading success through the utilization of his fourseamer up in the zone, especially versus right-handed hitters. The primary difference being that Oh knows where his fastball is going on a consistent basis and Wacha simply does not. Also, it helps that Oh carries the threat of a non-straight offspeed pitch (i.e the slider) to keep hitters off balance, whereas Wacha's primary secondary offering is his changeup.

Contact Rates (Plate Discipline Primer via FanGraphs)

Being able to limit contact on pitches out of the strike zone is one thing, but limiting contact on pitches in the strike zone is a completely different, much more difficult task. Yet, as you can see in the table above, only one MLB reliever has been better than Oh at limiting contact on pitches in the strike zone thus far in 2016 -- Danny Duffy at 69.4%. You would think a fastball-first pitcher would have trouble limiting contact on pitches in the zone against major league talent, but this has not been the case for Oh. Again, as already stated above, he is definitely benefiting from his two above-average offspeed offerings.

Using the Fourseamer to Set up the Slider (Slider Location to RHBs)

Given its right to left movement (also known as "glove-side" movement), the slider is a weapon Oh primarily uses versus right-handed hitters. As you can see in the heatmap, it is a pitch that consistently lives down and away, just outside of the strike zone. When discussing different approaches to pitching, "changing the eye level of the hitter" is a phrase used frequently. By consistently attacking righties up in the zone with his fourseamer, Oh is able to effectively sequence in his slider because not only does the hitter have to deal with a velocity difference of eight MPH, the hitter also has to deal with his eye level changing.

Some GIFs for Your Viewing Pleasure

92.6 MPH Fourseamer to Gerardo Parra

This was a three-pitch strikeout, and all three pitches were fourseamers on (or just off) the outside corner. Each pitch was a touch higher in the zone, forcing an extremely late swing from a pretty good hitter in Parra.

92.4 MPH Fourseamer to DJ LeMahieu

This strikeout took four pitches, and again, each pitch was a fourseamer. The pitch was clearly off the plate inside, but given ball one should have been strike three, this is not a surprising result. Live on the corners, and you will eventually get a handful of these calls.

95.0 MPH Fourseamer to Eugenio Suarez

Yet another fourseamer up in the zone for a swing and a miss...

85.5 MPH Slider to Jordy Mercer

And finally, as I have been suggesting this entire article, the threat of a down-and-away slider when he regularly throws fourseamers up in the zone often leads to embarrassing swings (and misses) by opposing hitters.

Credit to the @ThePitcherList for the beautiful GIFs. Make sure to visit their site: www.pitcherlist.com.