Hiroki Kuroda's Unique Place in International Baseball History

I want to talk about Hiroki Kuroda for a moment.

Maybe you haven’t thought about him much in the recent past. I wouldn’t really blame you, considering that he left the Majors back in 2014 and hasn’t really been in the public eye (in the US, at least) since. That’s totally fair; he had seven years as a solid starter in the majors, which isn’t nothing, but still…time moves on, you know?

I was basically in the same boat anyway, so I can’t really say that I blame you. Plenty of pitchers have good seven year runs, and even if you’ve like me and have devoted as much of your memory to random baseball trivia at the expense of most other useful things, you just can’t remember all of them all the time. But that just made it all the more surprising when I saw his name pop up recently in some research that I was doing.

In case you haven’t thought about Kuroda’s career lately, it’s worth noting that, when he debuted in the Majors way back in 2008, he was already 33, with over a decade of seasons in Japan already under his belt. Despite his rookie season coming at such an advanced age, Kuroda went on to post a surprisingly strong career line: in 1319 innings pitched, Kuroda posted a 986 to 292 strikeout-to-walk ratio, a 1.172 WHIP, and a 3.45 ERA (good for a 115 ERA+). All of that adds up to 21.7 Wins Above Replacement, in spite of the rather mediocre-looking 79-79 career record.

That would be a good run for just about anyone, but for a pitcher to post that in their ages 33 to 39 seasons is especially impressive! And not only that, he went back to Japan for two more seasons with his longtime NPB* team, the Hiroshima Toyo Carp.

*Nippon Professional Baseball

To have a run like that, at those ages, is pretty exceptional. In fact, Kuroda ranks 55th all time in pitching WAR after age 33. Even more notable are some of the names immediately around him: you’ve got a trio of Hall of Famers (Fergie Jenkins 22.8, Whitey Ford 21.6, Jesse Haines 21.6) and another trio of knuckleballers (Tim Wakefield 22.8, Tom Candiotti 22.8, R.A. Dickey 22.7). That’s interesting company, if nothing else.

And pitching that good late in your career isn’t exactly a guarantee that one is destined for Cooperstown (those knuckleballers are evidence of that, as are numerous others on the list), but it’s also certainly not nothing. Indeed, only 27 Hall of Famers are better. It’s certainly enough to make me wonder: how might Hiroki Kuroda have done if he had started his career in the Majors? Would he be looking at a possible Cooperstown induction? I decided to take a stab at it.




First, the background. Kuroda debuted for the Hiroshima Toyo Carp way back in 1997 at the age of 22. For some interesting trivia, he was one year older than fellow 1997 Carp rookie Alfonso Soriano. For some reference, by the time Kuroda came to the Dodgers, Soriano was already in his second season with the Cubs (his last of seven All-Star appearances), and in the clear decline of his career (he would post a 107 OPS+ and less than 4 of his career 27+ WAR the rest of the way).

The Carp finished third in the Japan Central League that year (out of six teams), the only time they would finish in the upper half of the division before Kuroda departed for the Majors. As a result of playing for rather mediocre teams, Kuroda had a pretty pedestrian 103-89 record. Along the way, he had some okay-looking numbers, with a 3.69 ERA, a 1.265 WHIP, and a 1257/445 K/BB ratio. All of that seems fine, kind of in-line with his major league career.

You know how his MLB career went, since I mentioned his career stats earlier. At least he got some more postseason success in America, appearing in the Championship Series three different times (2008 and ’09 with the Dodgers, 2012 with the Yankees). It’s not as good as winning the whole thing, sure, but it beats eleven seasons in the cellar. After that, he returned to Hiroshima for two more seasons. Thankfully, in his final season, they actually won the division for once! And the even made it to the Japan Series!* They lost to the Hokkaido Nippon-Ham Fighters, so it wasn’t a perfect send-off, but it was better than nothing.

*The NPB Championship

Let’s lay that all out neatly in one place so that it’s easy to compare. In the end, this was Hiroki Kuroda’s line in his thirteen seasons with the Carp:

124-105 W-L, 2021.2 IP, 3.55 ERA, 1.246 WHIP, 1461 K, 504 BB

Once again, his seven seasons in the Major Leagues, split between the Dodgers and Yankees, went like:

79-79 W-L, 1319.0 IP, 3.45 ERA, 1.172 WHIP, 986 K, 292 BB

And all together, his 20 seasons in MLB and NPB look like this:

203-184 W-L, 3340.2 IP, 3.51 ERA, 1.217 WHIP, 2447 K, 796 BB

Now, if you’re like me, you may have noticed something interesting comparing those lines. Namely, his MLB line looks really similar to his NPB line. That might not seem weird, except that generally players don’t perform the same in their late 30s as they do in their 20s and early 30s.

Of course, Hiroki Kuroda isn’t “most pitchers”; there are always oddities. Just because “most pitchers” don’t pitch into their 40s doesn’t mean that Nolan Ryan and Randy Johnson don’t exist. Still though, there are other explanations. For example, I know nothing about the NPB as a run-scoring environment. If the entire league plays like Coors Field, that 3.55 ERA looks a lot more impressive.

I ended up compiling run scoring data for the Japanese Central League (like MLB, the NPB is split between one league with the a designated hitter and one without; the Central League is the latter) to see how Kuroda stacked up against his peers. Once I have that, I can calculate an ERA+ for Kuroda.* I also collected how the Carp performed on offense and defense; I won’t be able to go through and compile exact park factors to adjust this rough ERA+, since Baseball-Reference doesn’t have as detailed home/away splits as it does for MLB, but it’ll be useful to have on hand as a reference, at least. And while I was collecting all of this league data, I figured I would calculate his Fielding Independent Pitching as well.**

*Baseball-Reference’s given formula for ERA+ is 100*[lgERA/ERA].

**FIP is an attempt to measure how good a pitcher is without defense by looking at only what they can control on their own, and it is normalized to work on the same scale as ERA. Baseball-Reference’s given formula for FIP is (13*HR+3*(BB+HBP)-2*K)/IP + league_constant, where league_constant is set so that the league’s overall FIP for that season is equal to the league’s overall ERA.

Below is a table of the findings. Going across, we have the league Runs/Game, Runs/Game per team for games involving the Carp (since R/G as a stat is on an individual team basis, and just adding runs allowed and scored by a Carp would tell us how many both teams score), league ERA, Kuroda’s ERA for that season, my rough ERA+ calculation:

Year	lgR/G	HIR R/G	lgERA	Kiroda ERA	~ERA+	FIP
1997	4.25	4.84	3.85	4.40	88	4.83
1998	4.04	4.41	3.67	6.60	56	4.70
1999	4.43	4.81	4.12	6.78	61	6.04
2000	4.24	4.66	3.91	4.31	91	4.47
2001	4.12	4.34	3.78	3.03	125	3.28
2002	3.97	4.35	3.58	3.67	98	2.99
2003	4.53	4.33	4.15	3.11	133	3.53
2004	4.73	5.00	4.39	4.65	94	3.36
2005	4.40	4.78	4.10	3.17	129	3.27
2006	4.12	4.10	3.68	1.85	199	2.70
2007	4.11	4.27	3.84	3.56	108	3.78
2015	3.42	3.14	3.25	2.55	127	3.55
2016	4.09	4.13	3.69	3.09	119	3.68
Overall	-	-	-	3.55	118	3.58

Overall, he was pretty good for Hiroshima. Those second and third seasons might seem rough, but it’s worth noting those weren’t full seasons, as he threw less than 100 innings in each. After those first three seasons, he was basically at a 90 ERA+ or higher, including that amazing 199 mark in 2007.

But it’s also worth noting that his numbers in the NPB are once again pretty similar to his MLB numbers. In fact, it may be even more stunning here; the overall ERA is 0.10 higher, the ERA+ is only 3 higher, and the FIP is just 0.03 lower. It’s possible that Kuroda was just remarkably consistent over the course of twenty years…but my suspicion is that the Carp play in a hitters’ park. I can’t really test that without more data, but the fact that games featuring them were fairly frequently above the Central League average over thirteen years, even as the Carp themselves were rather mediocre, leads me to believe that that 118 ERA+ is actually understating things.

In any case, this is a massive recontextualizing of his career for me. With a little over 2000 innings of 118 ERA+, he essentially had a career of a Cliff Lee (2156.2 IP, 118 ERA+) or a Chris Carpenter (2219.1 IP, 116 ERA+) before counting his American stats. All together, with 3340.2 innings and an overall ERA+ in the 115-118 range, Kuroda’s fairly analogous to players like CC Sabathia (3299.1 IP, 117 ERA+), Andy Pettitte (3316.0 IP, 117 ERA+), Mark Buehrle (3283.1 IP, 117 ERA+), and Dennis Eckersley (3285.2 IP, 116 ERA+).

That all seems to be a borderline Hall of Fame career, something in the neighborhood of mid-50-to-low-60s in terms of WAR. And while NPB isn’t quite on par with MLB in terms of quality (most of the studies I’ve seen have put it somewhere in between AAA and MLB), it’s worth pointing out that they have shorter seasons, which have eaten into his counting stats (including WAR) a little, and that our ERA+ calculation is probably undervaluing him due to park. It’s too many moving parts to say that he’s definitely such-and-such WAR and would have hit any specific milestones, but I think this makes for a solid baseline at least.

And, more importantly, I think this opens the door to an interesting conversation about the Hall of Fame (did you expect anything else from me?). So far, only one foreign star has come over to the US and played well enough to merit Hall talk, but Ichiro has been good enough since coming over that the discussions about him are less “Will he have what it takes to make the Hall without considering time in Japan?” and more “Would he have the most hits of all-time if he had started in MLB?”.

What happens when that line isn’t so clear? It’s still interesting that Kuroda’s numbers are so good, but even in a best case scenario, he still accrued something like two-thirds of his value in non-MLB leagues. The Hall of Fame has in the past proved reluctant to recognize players from non-MLB leagues in any capacity. Even getting them to recognize Negro League stars, something that seems pretty uncontroversial today, took direct lobbying from Ted Williams in his induction speech (among others). Other leagues haven’t been so lucky.

Of course, even in that piece I just linked, I noted that the name of the institution is the National Baseball Hall of Fame. It seems… at least intellectually consistent to be not inducting stars who played their entire careers in the Nippon Profession Baseball league. So what we have instead is something of a sliding scale, or possibly more accurately, a two dimensional axis. For players who split time internationally, how good must they have been, and how much of their time must have been spent in Major League Baseball?

I’m not sure that Kuroda measures up fully on either axis, for all the reasons that I covered. Of course, hypothetically, I wouldn’t be opposed to his case if there was a super-loud contingent pushing him for all of these same reasons, but that seems incredibly unlikely to happen. And since his career went fewer than ten seasons, he won’t appear on the ballot anyway, so it’s a bit of a moot point. But it’s still worth keeping in mind, because we may be facing this question sooner than you think. Maybe it’ll be Yu Darvish (7 seasons in NPB, currently 30 and in his fifth MLB season). Maybe Shohei Otani (5 years in NPB, may debut in MLB next year or maybe not). Maybe someone else entirely. Better to think about all of these things ahead of time so as to not be caught flatfooted when it happens, though.