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Hunting for Hyun-Jin Ryu’s weakness

Is there anything specific that caused his August swoon?

League Championship Series - Los Angeles Dodgers v Milwaukee Brewers - Game Six Photo by Dylan Buell/Getty Images

Hyun-Jin Ryu wasn’t allowed a full season to show us his skills, but in the 80-odd innings he did pitch, he was very effective. He put up a 1.97 ERA, 3.00 FIP, struck out 27.5 percent of batters and walked just 4.6 percent. But like everyone on the Dodgers, he got hurt. His own DL trip was related to a “pretty dramatic” (in Dave Roberts’ words) groin tear.

But it didn’t seem to slow him down much, as he was as effective in September a he was in May, and showed up big-time in the NLDS. He also got shelled in one of his two starts in the Championship Series He also had a pretty consistently bad stretch of ball coming off the DL, throwing four of his worst games of the year between August 21st and September 11th. All seasons have their own ebbs and flows. It could be that bad stretch was an anomaly, or maybe something a team like, say, the Red Sox could hone in on. Let’s take a look.

For reference, here’s all Ryu’s Game Scores this season, by date:

Hun-Jin Ryu 2018 Game Scores

"Date" GSv2
"Date" GSv2
2018-09-28 56
2018-09-23 74
2018-09-17 77
2018-09-11 35
2018-09-05 47
2018-08-31 65
2018-08-26 44
2018-08-21 41
2018-08-15 74
2018-05-02 44
2018-04-27 53
2018-04-21 78
2018-04-16 65
2018-04-10 78
2018-04-02 33

Game Score is a somewhat quick and dirty way of judging a starter’s outing, with higher numbers being better. We’re going to focus on the games from the 21st of August to September 11th, a period after he returned, but not including his first game back from the DL. That game, on the 15th, saw Ryu throw six shutout innings and allow just three hits and strike out six, with no walks. Then, four of his next five games were some of his worst. It could be a blip, or it could be a way to see if there’s a way to get to Ryu that the Red Sox, for instance, could exploit.

Ryu’s pitch mix is pretty typical for the season, a decent mix of fastballs, cutters and two-seams with changeups and curves mixed in, and a salting of sliders. During that stretch off the DL though, there was a slight shift:

Baseball Savant

Notably, he stopped throwing his two-seam/sinker nearly at all, focusing instead on the fastball, curve and change. In his final couple starts he did start throwing the two-seam a bit more, bumping it up to 3 percent of total pitches, or eight of the 266 he threw after his start on the 11th. One could say sample size issues loom, but that stretch I looked at contains 417 pitches, more than a third of the pitches he threw all season. So if it means nothing, the rest carries little more weight.

So what does this mean in the context of the playoffs? Ryu has three starts this October—the first a great one against the Braves where he shut them out for seven innings. According to Baseball Savant, in that game he threw 44 four-seam fastballs, 24 cutters, 21 changeups, 17 curves, and one two-seam fastball. So, that’s something.

He also had a terrible start, getting knocked out after recording nine outs and being blasted for five runs on seven hits by the Brewers. In that game Baseball Savant tells us he threw 28 four-seams, ten cutters, nine changeups, nine curveballs, and one two-seamer. So that’s… something.

This two-seam string I’ve found myself on, perhaps it’s a big red herring. Perhaps Ryu got hammered by the Brewers because it was their second time seeing him in less than a week, and they’re really great offensively, and he barely cracks 92 on a good day. That said, in his middle of the road October start, on the 13th, he did throw 12 two-seamers of his 72 total pitches. Which, again, is something.

Realistically, the way to beat Ryu is to hunt that four-seam—which he throws more than anything, though not enough to get comfortable—and take advantage of his below average velocity. It’s unlikely anyone on the Red Sox get to see him more than twice, not with all the pseudo-starters in the bullpen behind him. The Dodgers are showing us now what baseball will be in five or six years, with an ace or two in Kershaw and maybe Buehler, a bunch of Rich Hills and Ryus piggybacking each other and some guys that throw 105 at the back end. The idea of even the third starter is on the way out for the teams that will truly contend.

For now, though, for a man like Ryu who has good stretches and bad stretches as he muddles on the edges, he’s on the brink as soon as he steps on the mound. With his myriad arsenal it’s kind of hard to grasp what to expect, whether that two-seam or the cutter or the curve is the way to get to him is something that probably takes too much thinking. He’ll make a mistake—all pitchers do, even Kershaw and Sale—and that’s when the Red Sox will pounce... if they get the chance.

Merritt Rohlfing writes baseball things at Beyond the Box Score, Indians things at Let’s Go Tribe, and occasionally appears elsewhere on the internet, podcasts, and radio. Follow him for info @MerrillLunch.