Just how good is Shohei Ohtani, anyway?

Major League Baseball's free-agent market is expanding this winter with the addition of one of Japan's biggest stars, Shohei Ohtani of the Nippon Ham Fighters.

MLB's agreement with Nippon Professional Baseball made this a bit tricky, as Japanese free agents can't simply decide to play in the United States without the cooperation of their teams through the posting system, which compensates the Japanese club financially for losing a topflight player to the majors. Under the terms of an arrangement between the two leagues, the Fighters will be grandfathered in under the old agreement instead of the new one, allowing them to pursue a cap of $20 million rather than the $150,000 they stood to make under the new posting system -- thus giving the team incentive to allow its 23-year-old star to move on.

So the largest roadblock to Ohtani coming over to the United States has been neatly obliterated. But just how good will Ohtani be in the big leagues? Translating a pitcher's performance from Japan to the majors is complicated; we know far better how good a Clayton Kershaw or a Max Scherzer is than a star Japanese pitcher.

The good news: We have about two decades' worth of data on players regularly coming back and forth from Japan. Obviously it's not as much information as we have about Triple-A players, but it's enough to estimate NPB's level of play as somewhere between Triple-A and The Show -- although a bit closer to Triple-A.

Ohtani has been a dominating player in Japan. In 82 starts (and three relief appearances), he has posted a 2.52 ERA in 543 innings -- with 624 strikeouts (10.3 per nine innings) and 200 walks (3.3 per nine innings). He's also allowed just 24 home runs (0.4 per nine) and a mere 384 hits, an impressive 6.4 per nine innings. In other words, Ohtani has the profile you'd expect from an accomplished young star with a triple-digit fastball. As a hitter, he has a career .286/.358/.500 slash line and has played a good deal of games in the outfield, so when we say he's a good-hitting pitcher, we don't mean it in the left-handed-compliment sense, as when we praise Madison Bumgarner's offense while implicitly noting that pitchers hit terribly. Ohtani is in actual good-hitter territory.

But let's get to those aforementioned translations (which I'll refer to as zMLE -- or ZiPS major league equivalency -- from now on).