Kodai Senga and his ghost fork are exciting wild cards in the Mets’ rotation

You’re gonna hear a lot over the course of the 2023 season about the age of this Mets squad, and that is especially true of the starting rotation. The concern is not unwarranted—any team rolling the dice on four starting pitchers over the age of 34 is taking a pretty big gamble, even when some of those older guys are future Hall of Famers like Max Scherzer and Justin Verlander. It’s all too easy to envision a scenario where Father Time catches up to one or more of those pitchers, in which case the Mets could find themselves in a tough spot.

The good news is that the Mets are slated to have a rookie holding an important role in the rotation amidst all the veteran arms. Of course, that rookie is a thirty-year-old pitcher who has never pitched stateside. Still, Kodai Senga—while having a lot more variance in terms of his potential outcomes than most of the other pitchers in the rotation—represents an exciting high-upside variable for the 2023 Mets, and the fact that the organization signed him speaks wonders on the new and exciting principles that guide the front office’s decision making.

Indeed, the last time the Mets made this kind of investment in an unproven foreign player was when they signed Kazuo Matsui all the way back in 2003. That signing, of course, did not end up working out quite as hoped—but that still doesn’t erase the frustration that many Mets fans have felt as the organization almost wholly divested itself from the Asian market in the years since, letting numerous exciting players sign elsewhere without so much as whiff of interest. But now the Mets are being led by Steve Cohen, who has demonstrated an appetite for big and exciting moves, and Billy Eppler, who has been noted as being very aggressive in the Asian market over the years, including in his successful pursuit of Shohei Ohtani when he was with the Angels. As such, it seems that the organizational philosophy may finally be changing in that area, and inking Senga to a five-year, $75 million contract this offseason to fill one of the holes in the starting rotation may be just the beginning of that shift.

There have been two primary points of discussion about Senga in the early days of spring training. The first is in regards to his mysterious “ghost fork” pitch which has played a large role in his dominance in the Nippon Professional Baseball league. The second is about the challenges he will be facing as he seeks to transition into the major leagues. There are a number of big changes that any pitcher in Senga’s position will need to prepare for—including pitching in a five-man rotation and throwing a different baseball. People have thus watched Senga’s initial actions—a poor bullpen early on in camp, a significantly better showing just a couple days later—with a greater level of interest than most other players. That attention comes as we await to begin getting the answer to an all-important question: what kind of major league pitcher are the Mets getting in Senga?

We won’t know until we see him in regular season action, but the Mets are hoping that the success he had in Japan points to what he is capable of in the majors. Looking at his stats, it’s not hard to see why the Mets were willing to make such an investment in him:

There are some areas, like inconsistent control and injuries, that Senga dealt with at various times in Japan, and the Mets will hope that those issues will not hamper him too seriously moving forward. Still, on the whole, the numbers confirm his status as one of the best pitchers in Japan in recent years, and the team believes his repertoire—led by the aforementioned ghost fork and a fastball that touches the high 90s—will allow him to find success here as well. For his part, Senga has openly talked about the work he’s done at Driveline to prepare for the transition he will be making, and the hope is that the work he’s putting in there will lead to both continued development for him as a pitcher and for his adjustment to the majors to be as smooth as possible.

But of course, there will almost certainly be an adjustment—the Mets aren’t expecting him to replicate his 1.89 ERA from last season. So how will going from NPB hitters to MLB ones impact the kind of production we can expect from him? I went and took a look at some of the notable Japanese pitchers who have made the move to the states over the past several years. While this is not an exhaustive list, here are the jumps that each of these players made from their last season in Japan to their first season in the majors:

Daisuke Matsuzaka

Hiroki Kuroda

Yu Darvish

Masahiro Tanaka

Kenta Maeda

Yusei Kikuchi

While a lot of these players had solid overall rookie seasons, nobody should be surprised to see that all of them experienced varying levels of challenge upon making the transition to pitching in the big leagues—they may not be rookies in the traditional sense, but they’re still facing athletes the likes of which they’ve never faced in their lives. One thing that does strike me as interesting is that the guy with arguably the smoothest statistical transition is Kuroda—who, at 33, was a fair deal older than most of the other pitchers here when making the move to the majors. Maybe it’s just a coincidence, but it certainly seems possible that Kuroda’s advanced years made him more of a finished product in terms of his development as a pitcher, which thereby made him lose less of a step in his production. And at 30, Senga is also a bit older than most of these other pitchers, so perhaps we can hope for a similar story with him.

Of course, the flipside here is Yusei Kikuchi—a guy who had a very successful career in Japan, but who, save for some flashes here and there, has yet to really put it together on a consistent basis as a major league pitcher. As previously stated, you can’t avoid the risk you take by committing money to a dude who has never played against big league competition, and Senga could wind up playing out similarly to how Matsui played out for the Mets all those years ago.

Alternatively, he could go a route closer to that of some of the others guys mentioned above—guys who made All Star teams and competed for Cy Young Awards. While the potential for Senga to bust in the majors is real, the upside for him is tantalizing, and made him a worthy target for the front office to pursue as they seek to put a championship contender on the field.

The Mets will be heavily relying on Senga to help make those championship contending dreams a reality. They lost Jacob deGrom, Chris Bassitt, and Taijuan Walker to free agency—essentially putting them in a position where they needed to replace a #1, #3, and #4 pitcher. While Verlander is undoubtedly the guy the Mets are hoping will put up something close to that #1 output, Senga may be the guy most likely to replicate the kind of production that Bassitt put up in his one season in New York (3.42 ERA in 181.2 innings over 30 starts). If he can do that, the Mets will be well-positioned to repeat their success from last year. If he can do even more than that—if he can show flashes of the kind of stardom that he demonstrated in Japan—then 2023 may shape up to be an even more magical season.