The SF Giants promoted right-handed pitcher Kai-Wei Teng to Triple-A Sacramento on Saturday, bringing the 24-year-old prospect to the highest level of the minors for the first time in his career. The Giants acquired Teng in a trade with the Minnesota Twins back in 2019, and he has quietly climbed the organization's minor-league ranks. This season, Teng was repeating the Double-A level and recorded a 4.75 ERA in 12 starts with 68 strikeouts and 20 walks in 47.1 innings pitched. While his ERA is relatively unimpressive, both FIP (3.45) and xFIP (3.35) suggest Teng was pitching better than his traditional box score numbers suggest.
Teng was signed out of Taiwan by the Twins as a teenager back in 2017. Teng had an advanced feel of a versatile pitch mix for someone that young and was expected to move quickly through the minors. Teng reached full-season ball in 2019 as a 20-year-old and posted a 1.58 ERA in 79.2 innings pitched (14 appearances) with 88 strikeouts and 21 walks with the Twins and Giants Single-A affiliates.
Teng returned from the COVID-cancelled minor league season with a slight jump in his fastball velocity and an even sharper breaking ball. His newfound pitch arsenal helped him rack up 142 strikeouts in 95.2 innings pitched (21 starts) at High-A. However, Teng's command took a notable step back with his nastier pitches. His walk rate spiked to 12.7% and led him to post a career-worst 4.33 ERA.
Despite his struggles, the Giants promoted Teng to Double-A last season. All the trends from the previous season continued. He recorded 169 strikeouts in 136.1 innings pitched but surrendered 85 walks and managed a well below-average 5.22 ERA. Still, even with his struggles, Teng was only 23.
Teng has continued leaning more and more heavily on his slider this season and at this point, is essentially a two-pitch arm. His fastball can reach the mid-90s but projects as a 45-grade MLB pitch. He has, however, found an improved ability to locate his slider, which has helped him take this step forward.
While it has been nearly four years since Teng was traded to the Giants, he will not turn 25 until December. Barring a significant improvement in his command, fastball, or the development of a third pitch, it's hard to envision him sticking in a big-league rotation. With that said, if his fastball could add some velocity in a move to the bullpen, his slider could be enough to make him a viable middle reliever.
Teng will face a massive adjustment moving from the pitcher-friendly Eastern League to the hitter-friendly confines of the Pacific Coast League. Nevertheless, he will look to continue taking steps forward at the highest level of the minor leagues. For now, Kai-Wei Teng will presumably continue receiving an opportunity to prove he can stick in the rotation after the SF Giants promoted him to Triple-A Sacramento.
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