On January 2nd, 2019, the Seattle Mariners took a chance on a LHP from Morioka, Japan. A pitcher who was clocked at 96 MPH in high school, this pitcher was not lacking promise and without a doubt, turned a lot of heads. This pitcher was Yusei Kikuchi. Kikuchi started his professional career in the Nippon Professional Baseball’s Pacific League, playing for the Saitama Seibu Lions. In 8 seasons as part of the NPB, Kikuchi went 73-46 with a 2.77 ERA and 903 strikeouts in just over 1,000 innings pitched. His track record was very impressive, and due to that, he raised interest from nearly half of the MLB teams at the time.
Kikuchi eventually chose the Seattle Mariners, signing a 4-year, $56 million contract, bolstering the Mariners’ starting rotation instantly. At the time, the Mariners were in the early stages of a long-awaited rebuild following the departures of key players such as James Paxton, Robinson Canó, Edwin Diaz, and Nelson Cruz. For the Mariners, Kikuchi looked like the perfect candidate to kickstart the rebuild and become a staple in the starting rotation for years to come.
But, as many young MLB pitchers do, Kikuchi struggled out of the gates. Of course, Kikuchi had seen professional hitters for years and years before coming to the states, but none like the hitters that he saw day in and day out in his first season in 2019. Kikuchi stayed healthy, which was most important, but his numbers weren’t quite as expected. He went a suboptimal 6-11 with a 5.46 ERA and 116 strikeouts in 161 2/3 innings pitched. The more alarming numbers included a FIP of 5.71 and a strikeout percentage of 16.1% with a walk percentage of 6.9%. 2019 was a year in which Mariners fans were quick to assume that this signing was not worth it and Kikuchi wasn’t what the headlines had said. The abbreviated 2020 season was a little of the same, but if we look deeper into some of the stats, it did show progression. He still only posted a 2-4 record with a 5.17 ERA and 47 strikeouts in 47 innings pitched. But, unlike 2019, he posted a much improved FIP of 3.30 and a strikeout percentage of 24.2%. Batters facing Kikuchi also posted a .306 BABIP (Batting Average of Balls put In Play). What this tells us is that Kikuchi was getting quite unlucky, and he pitched much better than his 5.17 ERA showed. It wasn’t an outstanding season, but it showed promise.
Fast forward to today, May 17th, 2021. Kikuchi currently holds a 4.30 ERA over 7 starts with 45 strikeouts in 44 innings pitched. He has an impressive 25.6% strikeout percentage and a 7.4% walk percentage. His numbers are improving quickly, but the real question is: how exactly is he doing it?
The first, and probably most prominent factor, is the usage rate of his pitches. He is throwing his much-refined cutter more than he ever has, resulting in more groundballs and fewer home runs given up. According to Baseball Savant, Kikuchi is throwing his cutter 41.5% of the time and his slider 21% of the time, different from 40% and 16% from 2020. He is also using his four-seam fastball much less, 29.7% this year as opposed to 37.7% last year. Spin rate is up on all four of his pitches, and that shows in his much-improved whiff rate. Relying more heavily on his pitches that give him more movement has led to more strikeouts and in turn, better outings.
Secondly, I believe that Kikuchi is becoming more confident in throwing his pitches in any count. Much of the reason he was struggling in his first two years was that he was getting behind many hitters early in counts. This led to the heightened usage of his four-seam fastball and made him more predictable. This year, Kikuchi is walking fewer batters, and even when he is getting behind in counts, he is much more comfortable throwing his secondary pitches for strikes.
Lastly, Kikuchi is finally getting the results after a year of bad luck in 2020. In that year, opponents actually had a lesser hard-hit percentage and a lower expected batting average on balls they were putting in play than this current season. It wasn’t obvious that Kikuchi was set to succeed, but when looking at certain metrics, Kikuchi was getting quite unlucky. He was due to receive the results he deserved.
For Mariners fans, it seems as if Kikuchi can be the pitcher that management signed a mere two years ago. He is learning, growing, and progressing as a pitcher and a strong piece of a young and inexperienced rotation. If he continues to grow and adapt to major league hitters, Yusei could become a more than serviceable piece at the top of the Mariners’ staff. It will be incredibly interesting to see what the Mariners plan to do with the young arm as his contract expires in the next couple of years. The youth movement is on in Seattle, and look for Kikuchi to be a big part of that.
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