ANAHEIM, Calif. — Yusei Kikuchi became a different pitcher once he was traded to the Houston Astros at last year’s trade deadline. The more notable difference was the massive increase in his slider usage, but something that went under the radar was the change in his arm slot.
If you look at Kikuchi’s Baseball Savant page, you’ll find that his arm angle was 42 degrees, which was the same in the two years prior. But Kikuchi’s arm angle was consistently around 44 degrees as a member of the Toronto Blue Jays, and he lowered it down to around 38 degrees once he was an Astro.
This year, as an Angel, his average arm angle is 34 degrees.
Kikuchi started the season with an arm angle around 34 degrees, but has moved it back to levels near the 38 degrees he had it in Houston in his last couple of starts.
“I started throwing the backdoor slider more with Houston, and when you throw backdoor sliders, naturally, your arm slot goes down,” Kikuchi said.
Kikuchi also doesn’t read too much into his lowered armslot and doesn’t feel that it has changed how he’s pitched.
A recent study has found that lowering a pitcher’s arm slot also helps reduce the risk of arm injuries because it is less stressful on the elbow and shoulder, but Kikuchi said he hasn’t felt a difference in his level of soreness after starts since lowering his arm slot.
Another byproduct of lowering his arm slot is that Kikuchi is getting more horizontal movement on his pitches.
From last season to this season, Kikuchi’s fastball has gone from 7.9 inches of horizontal movement to 10.5 inches, his curveball from 4.9 inches to 5.7 inches and his changeup from 12.7 inches to 13.9.
The lowered arm slot has been working for Kikuchi. He’s sporting a 2.89 ERA since the trade to the Astros. So far, Kikuchi has a 3.01 ERA in the first 16 starts of his three-year contract that he signed with the Angels over the offseason.
Kikuchi has had to work for his 3.01 ERA this season, though, because he’s been allowing traffic on the basepaths at a towering clip. His 1.428 WHIP (walks + hits divided by innings pitched) is the third highest in the big leagues.
The biggest challenge for Kikuchi this season has been the walks. He leads all of baseball with 43 walks allowed. On a rate basis, Kikuchi’s 11.2% walk rate is the fourth highest in baseball and the second highest mark in his career.
The peculiar aspect about his elevated walk totals is the fact that Kikuchi is throwing the ball in the zone more than ever in his career. Kikuchi is in the strike zone 52.9% of the time, so how can he be walking so many batters?
The simple answer is that hitters aren’t chasing out of the zone.
Hitters are chasing out of the zone against Kikuchi 24.4% of the time, which is a career low and four percent lower than the league average.
“I think I might have been trying to be a little fine with my pitches,” Kikuchi said as to what could be the issue with his walk rates.
Not trying to be fine with his pitches has been an adjustment that’s worked for Kikuchi recently, as he’s only allowed three walks in his last three starts. Two of those starts include 7.1 innings of shutout ball against the Athletics while only allowing a walk and a hit, and seven innings of work against the Astros, where he allowed two runs and no walks.
The constant traffic on the basepaths raised questions about the sustainability of his low ERA, but if Kikuchi’s adjustment of not trying to be fine with his pitches continues to work, there’s no reason why Kikuchi can’t keep up his production.