Masahiro Tanaka bears the brunt of Yankees’ offensive struggles

The Yankees have been bad at scoring runs this year. And they’re especially bad at scoring runs when Masahiro Tanaka is on the mound.

That the Yankees are providing little run support for any of their pitchers is unsurprising, considering how poorly they’ve been hitting. The Yankees’ lineup of late has been bad at scoring runs, period, regardless of who is on the mound.

But even relative to the rest of the Yankees’ starting rotation, Tanaka has been deprived of run support. By a significant margin, Tanaka has received less run support during the current 2020 season than any other Yankees starter.

How much less? To get a feel for Tanaka’s run support stats in 2020 I compared his run support numbers to those of other starters on the Yankees. For those unfamiliar with run support metrics, RS/GS reflects the average runs scored by a team in games the pitcher started; RS/IP measures the average amount of runs scored by a team while a particular pitcher is in the game, on the mound.

So far this season, the Yankees have scored an average of 3.3 runs in games where Tanaka was the starting pitcher. For comparison, the Yankees have scored an average of more than five runs per start for other pitchers in the rotation with at least five starts this season.

Does that mean there is some truth to fans’ perception that the Yankees’ lineup is less productive when Tanaka is on the mound?

Among Yankees fans on Twitter, the sentiment that Tanaka gets no run support has been bouncing around for years. But in baseball, statistics don’t always support patterns which feel true to fans. Even if it seems like Mike Tauchman always strikes out with the bases loaded, or just because it felt as if Derek Jeter always came up with a big hit when the game was on the line, doesn’t mean those situational events actually occurred with more frequency.

Initially I remained skeptical of my perception that the Yankees’ bats go cold during Tanaka’s starts. I have found that it is extremely difficult to predict if analytics I research will reinforce the impressions I form while watching the Yankees, or if the numbers I find will contradict my impressions of the players, their patterns and tendencies.

To understand if the meager run support for Tanaka is statistically significant, I decided to calculate the standard deviation of RS/GS for MLB starting pitchers, using data pulled from Baseball-Reference. Tanaka’s run support stats in 2020 are pretty low, but do his numbers fall outside the bounds of what is considered typical for MLB starters?

Tanaka’s RS/GS of 3.3, while lower than both the league average and the average of his peers in the Yankees’ starting rotation, does not fall in the range of what would be considered unusually low run support from a statistical perspective. Out of the 277 MLB pitchers who’ve started games in 2020, Tanaka’s RS/GS places him at 240th. In other words, Tanaka’s run support stats—while not “unusually low”— put him in the bottom 15 percent among MLB starters.

It’s disheartening to watch Tanaka pitch a gem, like he did last Sunday, only to add another loss to his record—even if the game places less emphasis on a starting pitcher’s win-loss record nowadays.

Because run support isn’t something a pitcher can control, it tends to be a pretty flukey stat. Its utility, however limited, lies in the statistic’s ability to contextualize a starting pitcher’s win-loss record. Does a starter’s winning percentage seem off, or a bit too low, given his other stats? For Tanaka, who now boasts a 3.38 ERA and a decent 29:5 strikeout-to-walk ratio, a lack of run support is clearly the culprit.