After setting career-highs in wins (13), ERA (3.37), and innings pitched (200.1) last season, Merrill Kelly has been one of the best performing foreign-born pitchers in the major leagues this year.

This season, Kelly has the most wins in the National League (NL) (8-3) and is even better than last season, when he posted a career-best 2.92 ERA, 82 strikeouts in 77 innings, and a 1.10 WHIP (walks allowed per inning pitched).

Considered a fifth starter when he was acquired ahead of the 2019 season, Kelly’s ace-like performance since last year has been hailed as a “stroke of genius” by Arizona, who signed him to a three-year, $25 million extension in April.토토사이트

One of the best arms in the game, Kelly evolves from innings-eater to K-machine

A big reason Kelly, now in his fifth season in the majors, has exceeded expectations is his ability to confuse hitters with a variety of pitches in all corners of the strike zone.

From his major league debut in 2019 through last year, all five pitches in his arsenal – fastball, sinker, cutter, changeup, and curveball – have been at or above a 10% ground ball rate. This season, he added an outside slider to his repertoire against right-handed hitters, making him one of the most versatile pitchers in the league.

Kelly doesn’t just throw a variety of pitches, he throws them in the right places at the right time. Kelly’s style of pitching, which utilizes all areas of the strike zone, has been credited with creating a lot of confusion in the minds of opposing hitters.

In addition, this season, he has begun to throw his fastball combination (four-seam, sinker, and cutter) more often than he has in the past.

Distribution of Kelly’s four-seam fastball pitches in 2023 (Source: Baseball Servant)
BaseballServant

Kelly’s three fastballs and changeup have been praised for their tunneling effect (the synergy of different pitches forming similar trajectories). However, as his fastballs became more varied, he was able to confuse hitters even more, which naturally led to a significant improvement in his changeup’s ability to induce false swings. (34% career-high changeup swing rate this season).

As a result, Kelly’s strikeouts per nine innings have increased significantly this year to 9.6 (career average is 8), and this season he has become more than just an innings-eater, but a complete ace with excellent strikeout ability.

Constant work on his pitches has paid off with a reverse-export success story

Kelly was a pitcher who constantly worked to improve his pitches in the KBO, whether it was increasing the velocity of his fastball or honing his cutter, and he continued to do so in the majors.

In 2019, his rookie season in the majors, Kelly’s changeup had a small amount of vertical movement that was 15 centimeters lower than the average changeup of other pitchers with similar conditions (release point and velocity).

This season, however, the changeup has seen a dramatic increase in vertical movement, with Kelly’s changeup showing over 7 cm more vertical movement than the league average, and this improvement has made his changeup one of the most powerful in the league (changeup FIPS comparison: .906 in season 19 / .352 in season 23).

In addition to his changeup, his rising movement on his cutter and the drop on his sinker have both improved by more than 5 centimeters since his debut season in the majors (Season 19/23 OPS comparison: Cutter .767 / .536, Sinker .859 / .675), so Kelly’s efforts to improve his pitches are clearly paying off.

Kelly has established himself as Arizona’s ace pitcher (photo source: club social media)
Arizona Diamondbacks

Kelly’s leap to the top of the ML this season is likely to be an inspiration for many foreign players, including Eric Peddy, who is currently on a tear in the KBO, winning 10 games in the shortest time in history.

Meanwhile, his team, Arizona, has also defied pre-season expectations and is leading the National League West by four games over the Los Angeles Dodgers.

With 20 wins on the line at this pace, it will be interesting to see if the ‘hard work genius’ can maintain his status as one of the best starters in the league at the end of the season and lead his team to both the district title and the pennant.