Mariners vs. Giants: Yusei Kikuchi looked good, but why?

Yusei Kikuchi made his 2021 debut last night and looked like an All-Star caliber player at certain points in the game. The Mariners left-hander completed six innings, allowed three runs, and struck out 10 batters.

Kikuchi gets credit for a quality start but it was more of a “fantastic start” if you dissect his outing.

Yusei Kikuchi minimized his walks and threw strikes

Walks have been a major issue for Yusei since coming to Seattle. Last season, he was in the 32nd percentile of the MLB for walk rate. He averaged 3.83 walks per nine innings in 2020. In yesterday’s game, the Mariners starter walked only one batter. To build on that, he threw 67 of his 89 pitches for strikes and threw 18 first-pitch strikes (faced 25 total batters).

This is a huge positive out of his first start, and I hope he can continue to control the zone for the rest of the season. If he can, Kikuchi will be a difficult pitcher to hit against.

The Mariners starting pitcher’s spin rate was higher for all four pitches

All four of his pitches had higher spin rates than his averages from 2020. In 2020, his spin rates were:

• Cutter – 2,256
• Four-seam – 2,178
• Slider – 2,347
• Changeup – 1,453

Last night, his fastball spin rate ranged from 2,148 rpm to 2,572 rpm. But most of his fastballs were mostly in the 2,400s. His cutter’s spin rate was in the 2,500s, his slider was in the 2,700s, and his changeup was in the 1,800s. These are some pretty significant improvements if you tell me.

I don’t exactly know what led to these changes from 2020, but it might have something to do with the new baseballs. The league made some subtle changes which include a slight decrease in weight without changing its size. Baseballs in Japan were slightly lighter so the MLB’s change might be a reason for his uptick in rpm.

Yusei Kikuchi only made a couple of big mistakes

The Mariners southpaw only allowed six hits, and the most important ones were the two home runs he gave up to Buster Posey and Evan Longoria. Both veterans hurt the Mariners in back to back games with the long ball and those were the only runs allowed by Kikuchi. Posey hit a solo shot in the third, and Longoria hit a two run dinger in the sixth. Kikuchi gave up four other hits but they were all for singles so he was able to limit the damage.

Just from the eye test, he looked fantastic overall and everything seemed to be working. Kikuchi looked like the best version of himself and I am very excited to see how he does in his next start.