Through August 11th of this season, Hyun-Jin Ryu had an ERA of 1.45, despite a 2.85 FIP and looked like the probable NL Cy Young. Since then, he has pitched 19 innings and posted an ugly 9.95 ERA. What exactly went wrong for the Dodgers left-hander? Another soft tossing NL starter may be able to shed some light on the problem.

For his career, Cubs pitcher Kyle Hendricks has an ERA- of 76. Among all pitchers with at least 600 IP in that span, Hendricks ranks 8th in ERA-, ahead of such pitchers as Justin Verlander and Madison Bumgarner. When using FIP- in that same span, however, Hendricks falls all the way to 22nd, with the same minimum requirement. Over a sample size of this many innings, he was thrown 948.2 in his career, it is clear that Hendricks is not merely getting lucky and outperforming his FIP that way. No, he possesses some skill that enables him to produce an ERA lower than his FIP year after year. The question now becomes apparent: how does Hendricks do this?

In 2019 Hendricks has been in the 1st percentile in MLB in fastball velocity, and the 3rd in spin rate on the pitch. Yet the league has mustered all of a .139 BA and .316 SLG against the four seamer, while swinging and missing 28.1% of the time. The four seamer is far from being Hendricks’s featured offering, as he throws it only third most frequently of his four pitches. A sinker and changeup comprise 69.5% of all 2019 offerings from Hendricks, but as batters hit a combined .267 and slug .429 against the two pitches, these are likely not as vital to his success. Indeed it is the aforementioned four seam fastball that has the highest value per 100 pitches among his arsenal.

What has yet to be mentioned about Hendricks is his curveball, one that spins in the 87th percentile among all pitches of that classification and drops an average of 7.74 inches. Batters are helpless against it, with anemic an .186 BA and .209 SLG when he throws it. This answers which pitches Hendricks is using for his success, but doesn’t explain how he is doing this. Let’s explore some minor, but when compounded, major, factors.

To start with, Hendricks’s release point on all four of his pitches is nearly identical. This is especially the case with the two valuable ones, as he releases at 6 feet for the fastball and 6.1 for the curve. Both of these pitches possess above average movement. The vertical drop on the curveball was already discussed, but it also has 16 inches of vertical movement, as opposed to the league average of 10 inches. The four seamer possesses nearly 8 inches (7.97) of vertical ride. Additionally:

The heat maps for his four seam fastball and curveball show that, with the drop and horizontal movement of the curve, they are coming from the same line of sight for the hitter.

Tunneling is not the only thing driving Hendricks’s results. In 2019 he has thrown 47.5% of his pitches at the edge of the strikezone, compared to just 42.6%, the league average. Having indistinguishable pitches on the edges of the plate means that batters will rarely be making solid contact, which is proven by his 95th percentile exit velocity and 90th percentile hard hit%. He has also only walked a mere 4.7% of all batters he has faced, good for 96th percentile in the MLB.

So all of this gives us the Kyle Hendricks checklist on how to outperform your FIP consistently. You must:

- not issue walks
- live on the edges of the zone
- be able to tunnel at least two above average pitches

Following those three guidelines leads to inducing a high amount of soft contact, the most surefire way to keep an ERA from regressing to its corresponding FIP. Now let’s see what happened with Ryu’s sudden plummet in performance.

To start with, Ryu is suddenly allowing batters triple the amount of free passes he was earlier this season. Through his first 142.2 innings, Ryu had walked a minuscule 1.1 batters per 9 innings. In his last 19 innings it’s 3.3 BB/9, still league average, but with the subpar strikeout numbers of Ryu, subpar isn’t quite enough. That takes off one of the three parts of the checklist.

As for the second, if Ryu is walking more batters, it’s likely he’s throwing less pitches on the edge of the zone. What he is doing, in fact, is worse. Ryu has thrown less pitches in the zone overall recently, as well as inducing less swings on pitches out of the zone.

Down goes the second item on the list. Now for the third, we need to look at what Ryu throws. His two best pitches have been a cutter and changeup. Let’s see how well they’ve been tunneling.

Not even close. Ryu is leaving his changeup in the middle of the zone instead of burying it down, and he’s throwing the cutter over the middle of the plate. Without them tunneling well, which they aren’t given their respective paths of movement, this is a recipe for disaster. All three requirements for the Kyle Hendricks checklist are failed recently by Ryu. It’s no surprise that his hard hit rate is at its highest since May. He has lost the three crucial ingredients for inducing soft contact without elite stuff.

Kyle Hendricks tells us what’s been wrong with Hyun-Jin Ryu, but he doesn’t tell us how to fix it. This is rather unfortunate, because it had been very fun to watch Ryu flaunt his ERA in the face of his FIP, defying regression every start. Now it’s a grim experience, as regression has not only arrived, but brought reinforcements. Ryu will attempt to go back to his all-star ways, limiting walks and confounding hitters with location and pitch mix. Hopefully, he can regain the elite form from earlier this season and entertain us all in October.