Jen-Ho Tseng will make his MLB debut in the midst of a close pennant race. It was only a year ago that the 22-year-old finished a subpar season with the AA Tennessee Smokies in which he recorded a 4.29 ERA and 4.43 FIP while striking out 5.48 and walking and 2.54 batters per 9 innings, respectively.
Tseng learned from his first stint at AA, coming back strong to start 2017 by posting a 2.99 ERA and 3.28 FIP in 90.1 innings before being called up to AAA. On the brink of a call-up, he went on to register a 1.80 ERA and 4.25 FIP, the sum of which led to his second Cubs MiLB Pitcher of the Year award.
Prior to 2016, Tseng was projected to produce 1.5 fWAR through his first six seasons (~0.3 fWAR per season). After 2016, however, the Taiwanese pitcher’s numbers made him more or less irrelevant to public minor league evaluators, so we never got an update on his projection for 2017 and beyond. It was probably really bad, though.
Tseng clearly developed this year and overcame whatever troubles he was experiencing before embarking on a successful 2017. Using statistical models to project minor leaguers is fraught with limitations precisely because pitchers like Tseng sometimes confound predictive patterns. Despite poor projections, the Cubs front office and coaches, who feed on proprietary metrics that we only dream of seeing, feel as if the young righty is ready to contribute to a team trying to make the playoffs. To me, that says something,