Masahiro Tanaka on Saturday explained reasons for his abrupt return to the Rakuten Eagles just a few days before the team’s spring training camp was to open on Monday. I’m sure what he said was true, but it probably wasn’t the whole story.

Having said that, I doubt Japan’s media wanted the whole story. They want players to talk about player things: championships, fans, organizations, competition, contracts, teammates and so on. Tanaka mentioned the coronavirus once in his press conference, but not his family at all, which is fine but probably limits our understanding of the whole picture.

But let’s move on from that, and talk about 2021. Tanaka’s decision may not have been earth-shaking, but Japan definitely rocked. Most Japanese major leaguers only return to Japan when offers back home far outweigh the available MLB options.

Hiroki Kuroda reportedly left millions on the table to return to Japan. Tsuyoshi Wada and Daisuke Matsuzaka still had some value in the majors but nothing like the big guarantees SoftBank was offering.

Below are the five best seasons produced in NPB by Japanese former major leaguers. None of these were remotely close to their best prior to their leaving Japan, which is to be expected since most were past their primes when they left. I was surprised to see that the two best seasons were produced by post-Tommy John guys.

The funny thing from Saturday’s presser was Kazuhisa Ishii’s reminder that he still has a few more career wins than Tanaka. The former lefty does indeed, but Ishii pitched until he was 39 and his total career value is about three-fourths of Tanaka’s to date.

They both returned to Japan for their age 32 seasons after disappointing results the previous year in the big leagues, but Tanaka has been better at every step of his career along the way. Ishii was a lefty but Tanaka is two months younger at this stage.

People still remember the pre-elbow sprain Tanaka, who ran off 36 straight quality starts from Aug. 26, 2012 until he took the loss in Game 6 of the Japan Series, snapping a streak of winning 30 consecutive regular and postseason decisions. We remember that Tanaka bounced back from the Game 6 complete-game loss to save Game 7 and clinch Rakuten’s first, and so-far only, Japan Series championship.

But he’s not that pitcher anymore. He was a master of adjustments then, and no doubt is even craftier now, but the good fastball is not quite what it was, and I have to think the hitters in Japan, particularly in the Pacific League, are better than they were eight years ago.

The big difference, I suspect, is going to be how well he adjusts to batters who thrive on testing pitchers’ sanity, by poking good pitches foul and rarely trying to drive them. Japanese baseball is in some respects a different kind of challenge for pitchers and hitters.

Because it is baseball, it is hard, and will eat up and chew out some of the world’s best if they take their feet off the gas for more than instant. I doubt Tanaka’s transition will be as smooth as everyone expects, but because he is smart and highly motivated, I expect he can get over those hurdles better than anyone.

It’s going to be fun.