One Thing to Watch with Mike Soroka

The Atlanta Braves have hitched their rebuild to starting pitching. Whatever you think of that strategy, that's what they've done and they've littered their farm system with the best collection of arms in baseball. And in a system that’s stacked with so much pitching talent, there may be none more talented than RH Mike Soroka.

Soroka was taken in the 1^st round (28^th pick) of the 2015 draft and almost immediately made it known that his talent takes a back seat to no one. After signing, he started with Danville and went on to post a 2.10 FIP while striking out 25% of the batters he faced in his first season. That impressive performance earned him a spot in Rome for the 2016 season and all Soroka did was follow up his impressive debut with 143 innings and a 2.78 FIP in A ball despite just being 18. While other kids were graduating high school, Mike Soroka was dominating a pro baseball league.

These performances were so absolute and so dominant, that the Braves' front office decided to do something a bit unusual and very aggressive. They decided to jump Soroka directly to AA to start the 2017 season, completely skipping High A ball, and make a very clear statement that their belief in the right-hander was as real as his talent.

He hasn’t disappointed. Unbelievably at 19, Mike has a 2.38 ERA and a 3.08 FIP in 105 innings at Mississippi this year and his still striking out almost 22% of batters faced. Wednesday night against Biloxi, Soroka arguably had his best start of the year throwing 7 innings with 2 hits 2 runs and 12 strikeouts. At 19, he truly is one of the best prospects in the Braves' system and really, in all of baseball.

But there is one thing I think it’s going to prudent to watch as Mike progress up the minor league ladder and eventually to the majors. Mike has a three-quarter arm slot in his delivery and that comes with some challenges. The principal challenge, as is with any pitcher is health but that’s not the point of this post. What we’re going to need to watch with Soroka are his platoon splits.

Every pitching prospect in baseball, at some point, has to solve the mystery of getting opposite handed hitters out, and it’s not always easy. Guys like Julio Teheran and Mike Foltynewicz still struggle with it to this day so success certainly doesn’t always come quick. Or at all.

But the reason it’s such a big deal for Soroka is because of that three-quarter arm slot. Historically there is a correlation between guys who throw with a lower arm slot and guys who have more severe platoon splits. The reason is simple enough to explain. Generally speaking batters hit pitches moving towards them more effectively than they do pitches moving away from them. This is the entire reason why platoon splits exist. Most of the pitches a RH pitcher throws move towards a left-handed hitter and vice-versa. The one exception is typically a change-up.

The way the physics of a change-up work is the more you can get on top of it as you throw it, the more horizontal movement it’s going to have arm side. This is the most prominent weapon pitchers have used against opposite handed hitters because typically it’s the only pitch they have that’s moving away from the hitter. But because getting on top of the pitch helps so much, it’s not hard to understand why lower arm slot guys have trouble throwing it and why historically, they have higher platoon splits.

Really I guess you could say what we need to be paying attention to is the development of his change-up. Fangraphs put a 45 on it. (20-80 scouting scale) MLBPipeline has it at a 55. Who knows where it ends up but where we’re going to see the fruits of that development most is against LHB. Looking at his minor league numbers, you can start to see it a little. In 2015 his OPS against vs RHB was .303. Against LHB it was .864. That split improved considerably in 2016 with a .603 OPS against vs RHB and .648 OPS against vs LHB.

Honestly though, it’s going to be in the upper minors and his first couple years in the majors where we’re going to see how severe this problem is. His splits in AA this year are a .471 OPS against RHB and a .747 OPS against vs LHB. So there is something there. Again, this isn't a problem as much as it is just something to watch.

Every pitcher has to solve platoon splits. There's plenty of guys in the majors still trying to figure this stuff out. But the arm slot correlations are real and the explanations behind them make perfect sense. Soroka is a first class pitching prospect and his minor league career numbers speak for themselves. But how he develops that change-up and consequently how he handles LHB will ultimately decide how great he can be. Because the talent is there.