A tale of 2 catchers…

… or how many times can you beat a dead horse?

… with new notes about Tomoya Mori’s defense at the end.

I wrote recently about the Seibu Lions’ catching situation. The Lions this year became the first team to win a pennant and finish last in their league in ERA since the 2001 Kintetsu Buffaloes.

Having added the 2017 data for opponents’ offense against each catcher in NPB. This year, Ginjiro Sumitani was shoved aside as Seibu’s No. 1 catcher so that Tomoya Mori could hit more, and the Lions ERA soared from 3.53 (third best in the Pacific League) to 4.24.



I have heard that catchers’ ERAs — like batting average on balls in play against a pitcher — are not very predictive. I’m not going to replicate Sean Smith’s research here for NPB just yet, and I may be freaking out too much with small sample sizes BUT, when I saw the batting averages, on-base percentages and slugging averages against the three principle Lions catchers over two years, I was taken back.

First, the numbers for 2017:

2017 offensive results against the top three Seibu catchers.

Now the numbers for 2018, when Sumitani became No. 2 and Mori spent less time as a designated hitter and more time throwing out would-be base stealers:

2018 offensive results against each Lions catcher.

In 2018, Sumitani caught roughly half as much facing 1,433 batters instead of 3,233, but other than that and a poorer performance against base runners, his two seasons were carbon copies.

  • Batting average against: .247 (2017), .241 (2018)
  • On-base percentage: .308 (2017), .309 (2018)
  • Slugging average: .373 (2017), .374 (2018)

You can find the data for opposing hitters’ offense against NPB catchers in 2017 and 2018 here in roman characters and Japanese: 2017 romaji, 2018 romaji, 2017 日本語, 2018 日本語

I know this isn’t evidence that the Lions’ inflated their team ERA by making Tomoya Mori their No. 1 catcher, but it’s not a good look.

Something I was going to mention that on this week’s podcast but didn’t get around to it was whether Mori did more poorly in different counts than Sumitani or Masatoshi Okada. And it appears that he did in 2018. When the count was even, batters did quite a bit worse against Mori as they did against Okada and Sumitani. (.680 OPS vs .725 for Okada and Sumitani combined). But when behind or ahead in counts, Mori was worse.

I had speculated that Mori might be too predictable with runners on first since he improved a lot at throwing out base stealers this season, but there is  no hint of that in the data.



The bad news for the Lions is that Sumitani, who started all of Seibu’s postseason games behind the plate, has filed for free agency. In addition to lefty Yusei Kikuchi, who is being posted, and whose games Sumitani caught, the Lions could also lose slugging second baseman Hideto Asamura–who has also filed for free agency. If there is any good news there, it is that Okada, who began his career like Mori as a hitter who could catch, appears to be developing into a good game-caller.

Notes: After being criticized on Twitter for stating the fact that opposing batters hit better when Mori caught than when Sumitani or Okada did with the same pitchers, I mentioned my perception that Mori is not as good at blocking pitches. One of my followers disagreed, so I looked.

Mori was charged with a lot of passed balls BUT had fewer wild pitches charged to his pitchers, so the net effect was that he let relatively few runners advance on pitches that got past him. Is Mori weak at blocking balls? I don’t know, but the raw data I’ve seen doesn’t support that.

Jim Allen

sports editor for a wire service in Tokyo

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