A glance at Iwakuma’s recent struggles

 It goes without saying: every starting pitcher, no matter how talented, is going to throw a clunker once in a while. Even the great Clayton Kershaw allowed seven earned runs in a May start against the Arizona Diamondbacks, though that’s really his only blemish in an otherwise terrific season. So, as good as Hisashi Iwakuma has been for the Seattle Mariners this year, there’s little doubt that one would be able to look back on the season as a whole and pick out a handful of starts in which the right-hander was less than stellar — which brings us to a conspicuous last two weeks of from the No. 2 starter.

On Wednesday night, the Mariners lost a very winnable game to the Houston Astros who’ve been riding a hot streak of late. Normally with Kuma on the mound a victory seems easily within reach, as long as the bats don’t forget to show up. However in this contest, the bats didn’t provide much help and Iwakuma gave up four earned runs in four and one-third innings of work. A lack of offense on any given night has been a regularity for the 2014 Mariners — though they’ve become more consistent as the season has worn on — but a fourth-straight poor outing from the right-hander? It would appear that perhaps something isn’t quite right.

Over his last four starts, Iwakuma has allowed 15 earned runs in 18 innings of work which includes an outing against the Washington Nationals in which he gave up three home runs, all solo shots — he had given up just 14 entering the game. His ERA over that period is a gaudy 7.50, but his 4.29 FIP and 2.96 xFIP suggest that he hasn’t performed as bad as his earned run average would suggest. That’s good news considering he only allowed four walks while striking out 18 batter during that stretch, and his 25 percent home run per fly ball rate is double the 12.1 percent rate he’s produced all season.

Naturally, we start to wonder if there’s some cause of Iwakuma’s struggles over this period considering how dominant he had been prior. It doesn’t appear to be a mechanical thing and there’s no reason to believe that the starter is batting any type of injury aside from the regular fatigue that comes in to play through the course of an entire season. Prospect Insider’s Jason A. Churchill wondered on Twitter Wednesday night if Kuma had been throwing more splitters than usual, and thanks to this chart via BrooksBaseball, we can see that in fact, he has increased his usage of the splitter over his last four outings.

 Iwakuma has now made 25 starts on the year and averages a tick over 91 pitchers per start. Of those 91 pitches, just under 25 are splitters on an average basis. Make no qualms about it, Kuma is a sinkerball pitcher and thus has relied on it about 35 percent of the time in 2014. His splitter is used about 27 percent of the time and just 13 percent of his pitches are four-seam fastballs as well. In his last four starts — the period in question — the 33-year old has utilized his splitter 34, 22, 32, and 39 percent of the time respectively, three of those four numbers would be considered above average within the context of this season.

Now, in Kuma’s August 14th start against Philadelphia he threw eight shutout innings and 27 percent of his pitches were splitters. On another instance during July against Oakland Iwakuma took a shutout into the ninth inning before yielding a two-run home run and used his splitter 26 percent of the time. There was also a start in June versus Texas in which the right-hander allowed one run in eight innings of work while relying on his splitter for 34 percent of his pitches — several percentage points higher than his season average.

[pullquote]Iwakuma has mixed in a cutter at various points in the season for the first time in his career. He’s thrown it no more than six time during a single start and many it isn’t used at all. Kuma has also utilized his curveball less in 2014 than he has in the past.[/pullquote]

The thing that makes a splitter effective is that during delivery, it should appear practically identical to the delivery of a four-seam fastball — the difference, obviously, is that the splitter will break several inches and in some instances be a couple ticks slower than the fastball. As mentioned, Iwakuma relies heavily on his sinker and on only three occasions this season thrown it fewer than 30 percent of the time. In the first half of the season Kuma was using his splitter about 26 percent of the time compared to 29 percent in the second half, so he had started to utilize it more frequently earlier than just this recent stretch. Although the reality is that on average it’s only a couple more times each outing that he’s actually throwing the pitch.

It’s tough to really make much about a few starts worth of data in relation to why Iwakuma’s production numbers are down. For what it’s worth, in his first two years in the majors he threw a splitter approximately 22 percent of the time so the 27 percent usage thus far in 2014 is an increase, but it isn’t as if it’s significant. For context, out of every 100 pitches the right-hander throws, five more have been splitters in 2014 compared to 2013.

Perhaps the more interesting factor, which Churchill also mentioned on Twitter, is Iwakuma’s use of his four-seam fastball. Naturally sinkerball-pitchers rely heavily on their sinker or a two-seam fastball, but it’s curious to note that the right-hander has thrown four-seamers just 13 percent of the time so far this year which is a fairly substantial drop from the 28 percent mark in 2013 and 30 percent mark in 2012. It’s common for pitchers to set up their splitter with a four-seamer since, as mentioned, the mechanics of both pitches are very similar.

Perhaps Iwakuma’s decreasing fastball use is more concerning than his increased splitter use, but at the end of the day, we’re still dealing with too small a sample size to make much about. The decreasing fastball use is interesting because it’s occurred over a few years now, but it’s typical for pitchers to stick with what’s working. If Kuma feels his splitter is his best pitch on a certain night, naturally he’s going to stick with it. Same for his fastball, sinker, curve, or slider. But it’s rare that a pitcher cuts their four-seam usage by half within a year’s time.

Whatever the case, Kuma has seen a spike in his BABIP over this four-start stretch — a .375 mark compared to the .284 he’s put up on the season. Could we point to the fact the right-hander has simply given up more hits and been slightly unlikely over the last couple weeks? Certainly. It’s not as though he’s had noticeable control problems and although his walk rate doubled in that period, it’s still the second lowest in all of baseball.

Iwakuma will be fine as this appears to be no more than simply a rough patch. The use of his fastballs is fascinating, but it’s difficult to draw many conclusions without more data to crunch. For all we know, the right-hander could throw eight shutout innings while using his splitter 40 percent of the time during his next start.

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Tyler Carmont

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10 Comments

  1. Agreed, would love to see Paxton and Felix top this rotation for a long time. If Walker can get there too, even better.

    I could envision a possibility where the M’s entertain trading Walker, but to me, his value could still be down. Doesn’t mean the M’s couldn’t get a Soler-type of player in a potential deal, but it’d probably require more pieces than just those two to make it work.

  2. And it wouldn’t surprise me if Walker is traded over the winter. Most agreed that one of Walker or Paxton could be dealt for the right position player. Most were hoping that at least one panned out into an ace and the other could fetch a shiny young position player. JZ tried to move Walker for Upton but it was caboshed. I don’t think most expected Paxton to be the guy that turned into the ace out of the two but that is what is happening. I could see JZ begin content with that and moving Walker for a bat in the offseason.

    One team looking for the right young pitcher to add to their team full of young hitters are the Chicago Cubs. I think a Walker for Soler deal could make some since.

    The Cubs have Billy McKinney OF, Kyle Scwarber OF, Albert Almora OF, Jorge Soler OF, Arismendy Alcantara IF/OF, Addison Russell SS, Javier Baez SS, Kris Bryant 3B, Anthony Rizzo 1B, Starlin Castro SS who are all penciled in as regulars over the next few years. Somethings got to give. 10 guys for 7 spots.

  3. Yeah, it’s always been a question of Paxton’s health. If he can stay healthy I think he puts up a magical season. His numbers and stuff isn’t a fluke at all. The kid is really really good. Just hoping his new arm slot doesn’t mess up his shoulder. But if he can stay healthy, him and Felix make the deadliest combo in baseball and then add in Iwakuma and you have a knock out trio.

    Hoping Walker can get there. Not convinced yet.

  4. Kuma has lived down in the zone — and found plenty of success there — all season. Perhaps, as maqman mentioned, hitters have made the adjustment and he simply hasn’t yet? Of course there’s the matter of execution, which is no easy feat, but it seems as if as soon as a runner gets to scoring position, Kuma gives up an extra base hit lately.

    I agree that Paxton could open 2015 as the club’s No. 2 starter, and the sky is the limit for him, but I’m not quite ready to class him that high yet. I actually like the Erik Bedard comparison: tough to hit, high strikeouts, dominating stuff, but health will forever be an issue. Paxton’s shown that the flashes he showed in late 2013 aren’t a fluke. Personally I think he’s an ace in the making, but I want to see what a healthy 180-innings over a full season looks like first. Then we can go from there. Isn’t the thought of a Felix/Kuma/Paxton/Elias/Walker rotation next year tantalizing?

  5. He has hit a wall. And frankly hitters are keying on everything down in the zone. That’s all they are looking for and sometimes they swing through the pitch and sometimes they connect. And you are right, his command has become a little erratic.

    Right now I feel Paxton is a better pitcher the Iwakuma and frankly I think next year Paxton only gets better and will seriously be in contention for the AL CY. I think people will start mentioning his name as one of the top 2 or 3 best LHP in baseball. He’s going to be that good….IF HE STAYS HEALTHY!!

  6. That’s a really good question. It doesn’t appear that he is labouring on the mound, and it’s not as though his innings are that high yet. I want to say it’s bad luck, ie. Pujols smacking a double with the bases loaded, and he hasn’t had quite his usual pinpoint command, but it certainly begs the question as to whether or not something else is going on. His early-season injury was a sprained finger so it’s not as though he’s aggravated that in the same way a pitcher could have elbow or shoulder soreness come back. It’s strange, that’s really all I know at the moment.

  7. So Kuma lays another egg yesterday. Any ideas about his health? Could he be hurt or just tired?

  8. Kuma and Felix might take a leaf out of Young’s playbook and try some high heat on occasion, even Trout has a problem with that. Nowadays every hitter is looking for balls down in the zone. Make them move their eye level more often, that helps all the other pitches more effective.

  9. It also seems opposing hitters are adjusting to Iwakuma and Felix. You can tell in some at bats that hitters are looking for pitches down in the zone (Iwakuma’s splitter and Felix’s change). Our pitchers and catchers need to adjust and start working the corners, or make a better effort at mixing their pitches. Our pitchers have become way too predictable.

  10. I too think he will be OK, but his struggles come at a crucial time when the team needs him. Starting pitching as a whole is going through a rough patch. Sure hope they can pull it together!

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