Jeff Passan declared it, and so it must be so: It's time to appreciate Shota Imanaga. As everyone anticipated before this season, the mid-May series between the Chicago Cubs and our Pittsburgh Pirates has gifted us some of the most exciting starting pitching so far this season. There's Paul Skenes, the 21-year-old rookie for the Pirates whose stuff is so obviously nasty that he makes everyone fear for the state of his UCL whenever he pitches, and then there's Imanaga, the 30-year-old rookie pitcher for the Cubs, who is in some ways the exact inverse of Skenes: a 5-foot-10 lefty throwing 92 mile-per-hour fastballs from a low arm slot.
Imanaga knows how to play to a crowd. In his opening press conference, he prepared an English statement for the benefit of the fans. "Hey Chicago," he said, and then waited out the laughter and applause. "What do you say? Cubs are gonna win today." On Saturday, Imanaga did his part in blanking the Pirates over seven innings, lowering his ERA from a league-leading 0.96 down to a league-leading 0.84. For all that people see "Cubs pitcher with a low-velo fastball" and by heuristic default to "Now there's a guy who simply gets muddy in all of his starts," Imanaga is absolutely clean with it.
In Kyle Kishimoto's breakdown for FanGraphs on how Imanaga does what he does, he notes that Imanaga's splitter doesn't have the dramatic movement that people usually associate with nasty splitters. Most of Imanaga's success comes from his command; still, he has the sort of repertoire—two-pitch, a rising fastball with tons of active spin consistently up in the zone, and a splitter very consistently down in the zone—that makes me wish that broadcasts had a better angle for lefty pitches with movement. Under the traditional angle, Imanaga's pitches always appear flattened. Fortunately enough, the batters reveal what the camera does not.
Just ask Jared Triolo. In his first at-bat, he got ahead of the count before Imanaga was given a generous strike at the outer edge of the strike zone. He just barely managed to foul off Imanaga's bottom-of-the-zone splitter next, and that's when Imanaga launched his fastball to the corner opposite where his splitter was. Triolo took a goofy short swing at a pitch well above the strike zone and struck out. Triolo's second AB lasted a few more pitches, but didn't end much better: Imanaga threw another high fastball after a bottom-of-the-zone splitter, and this time, Triolo's swing missed badly enough that his bat flew into the netting behind home plate. (Triolo would get a measure of revenge with a single in the seventh inning.)
Imanaga was the lesser-hyped Japanese pitcher coming in this year, visible in his contract alone, and while Yoshinobu Yamamoto is still no slouch, Imanaga has so far been the one to really look out for. The primary concern about Imanaga before he came to MLB was in his extremely high fly ball rate, and corresponding home run rate. So far, the concerns have been unproven: Imanaga's allowed just three home runs over 53.2 innings pitched so far this season, a HR/9 rate of 0.5. But that number isn't necessarily sustainable. Imanaga has a fly ball rate of over 35 percent and is currently rocking a mere six percent HR/FB ratio (funnily enough, it's worth noting that one of his three home runs allowed this season came off of a line drive), while the league average for HR/FB ratio has, in recent years, hovered between 14 and 17 percent.
You'd naturally fear what will happen for Imanaga when the weather starts to heat up even more, but despite concerns about wind and so forth, Wrigley Field has, in recent history, been less homer-friendly than you might expect. There is still cause for optimism that Imanaga will be able to maintain a reasonable home run rate. Namely, Imanaga benefits from the uppercut approach that MLB hitters take—the same uppercut approach that has made consistently located fastballs up in the zone such a danger—and his contact metrics speak kindly about the fly balls that he has allowed: Hitters have gotten under them around 70 percent of the time.
So even if Imanaga comes down to earth a bit, it shouldn't be a hard crash but a sort of stumble. His peripherals in FIP and xERA are still kind, and anyway the point of buying into a mania is also believing wholeheartedly that it will never end. Thanks to the Cubs' run support, Imanaga was saddled with a no-decision for his start against the Pirates, but thanks in large part to Imanaga, the Cubs managed to win the game anyway away off a bottom-of-the-ninth walk-off. In retrospect, we can read Imanaga's initial press conference appearance as a statement of intent: Hell yeah, the Cubs are going to win it today.
