Paul Articulates - Do the numbers travel over the Pacific?

There have been quite a few baseball players that have parlayed their success in Japanese baseball into careers in MLB.  Since the notable success by hall-of-famer Ichiro Suzuki, MLB general managers are constantly monitoring the data for stars in Japan that are willing to move east to the US.

In an off-season where the Mets leadership is very focused on improving last year’s team, it is expected that they will look at every source of players including Japan.  Of course that also goes for all the media speculators that like to propose trades and acquisitions for the Mets so we certainly see our share of recommendations to sign sluggers and/or pitchers from Nippon Professional Baseball (NPB).

The first question that comes to mind when one considers the transition of any player from a foreign league to MLB is, “how will their performance translate”?  If you subscribe to the theory that the talent is better in MLB or if you just believe that the environment is different, everyone would acknowledge that stats in one league don’t necessarily predict stats in MLB.

I have had these thoughts and decided to use some available data to generate a tool to project future performance in MLB.  I looked at a sample of players that have had significant time in both Japanese baseball and MLB.  By significant time I mean at least 1,000 plate appearances in each league.  To me, that creates enough statistical significance to allow performance to be compared.  To be fair, not all players spent their time in these leagues at the same time, so there could be some variability in the talent they competed against, the equipment used (bats, balls), and the environment they played in.  

Below is a table with my results. I selected ten current or former players with the experience mentioned from Ichiro to Shohei to guys that just had healthy contributions to their clubs.  As you can see from the data, the average drop in both batting average and on-base percentage was between 7-8% between the performance in Japan and the MLB stats.  Slugging percentage was a more significant drop, just over 13%.

The necessity of this comparison becomes evident when recommending the acquisition of a player from a foreign league to replace a current MLB player to improve the team.  

Let’s take a case in point.  The Mets have struggled to field a third baseman since the departure of David Wright that gives them a power bat and excellent fielding.  Brett Baty seemed to be the new ray of hope, but he has had several ups and downs.  At one point he was replaced by Mark Vientos, who had a stellar 2024 season at the plate but has always had defensive shortcomings.  Baty seems to be on the rise again, but it is difficult to predict if he can reach and sustain a level of performance that will get the Mets to the next level.  The domestic market for third basemen includes some very good players like Nolan Arenado and Alex Bregman, but Arenado is well past his peak and Bregman will be asking for huge compensation as a 32-year-old free agent.  

So what if you looked west into NPB for a star third baseman whose team is willing to post him?  Look no further than Munetaka Murakami, an established power-hitting third baseman who has already received several accolades in NPB such as four-time all-star, two-time central league MVP, and 2022 triple crown winner including a massive 56 home runs.  "Murakami-sama" as he is known in Japan, has posted a career slash line of .270/.394/.557.  That compares very well with Bregman’s career line of .272/.365/.481 and looks much better than Baty’s .232/.295/.371.  Murakami will probably get some attractive offers from MLB teams. Since he is already 25 years old, he is not restricted to an international signing bonus and team control.  That said, his contract may come at a discount to Bregman’s expected AAV. 

If you apply the derating factors from the table presented earlier, the picture gets more cloudy.  If the average reduction in statistics from NPB to MLB follow the trend, Murakami would only be expected to slash .249/.365/.483.  Baty is on the upswing and hit .254/.313/.435 last year.  He is under team control for four more years and would be expected to improve – a value price, but what is the upside?

The challenge to David Stearns is to determine if it is in the best interests of the Mets to stick with Baty, who even in arbitration years will only make around $10M or to shell out big money for Bregman who will likely seek upwards of $30M AAV for at least six years, or to sign someone like Murakami who at only 26 years of age next season would command a healthy salary and a longer duration – up to 10 years.  

Only Shohei Ohtani registered better numbers in MLB than he had in NPB.  One could argue that he had not yet reached his prime when he left for the Anaheim Angels back in 2017 at the age of 23.  That argument could also apply to the young Murakami. If only Stearns had a crystal ball.