The subtle reason Twins relievers have cost them close games (free post)

With games in the balance, Twins relievers are allowing inherited runners to score at a crazy rate. Twins GM Thad Levine thinks that will be corrected.

The 2021 Twins bullpen has been bad, a fact that will surprise approximately zero people reading this column. It may not even surprise you to read that the Twins have been especially bad at stranding inherited runners. But would it surprise you to learn that one of the Twins’ biggest shortcomings in the bullpen this year has basically nothing to do with Álexander Colomé?

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The 2021 Twins and inherited runners scoring

In 2019, the most recent full season of MLB, the Arizona Diamondbacks were the best bullpen when it came to refusing to allow inherited runners to score. Arizona relievers let that happen on just 23% of the time. Oddly enough, the worst bullpen in the league that year was the future World Series Champs, Washington Nationals at 42% of inherited runners let in. (Remember that the Nats got off to a terrible start to the year and their bullpen was a weak point basically all season; they restricted the number of pitchers they used in the postseason and rode their starters.)

In 2018, that range from best to worst at Inherited Runners Scoring Rate was 24% at the good end and 38% at the bad side of the ledger. So that’s roughly the expected range we’re dealing with. (For the curious, the league average is about 35% this year; so you can expect that when a pitcher enters the game with runners on base, about 1 in 3 of them will come around to score, on average.)

I prefer to work with range, because using an average would strip the context of the Twins’ bullpen performance – or at least ability – and suggest that all 30 teams have an equal bullpen and the rest is just good or bad luck. I don’t believe that’s how it works! Good bullpens should strand runners more often than bad bullpens, in general, and the total number of opportunities would depend on the quality of the last reliever and the manager’s preference for switching arms frequently.

The 2021 Twins, you may have guessed, lead the Majors in this rate of allowing their inherited runners to score, at a whopping 63%. Twins relievers have entered the game with 43 runners on base, and 27 of those runners have scored. That’s much worse than average, and much worse than the even worst full-season numbers for the past few years.

Note that this is not one that can be attributed to the early poor performance of Álexander Colomé. He’s always come into games with clean bases, and while this note isn’t about him, it’s fair to say that’s been a relative disaster so far for the Twins. Caleb Thielbar has allowed 8 of his 9 inherited runners to score; Tyler Duffey 5 of 7; and Taylor Rogers 5 of 6.

And based on those names, you can guess that many of these were in situations with games hanging in the balance. If you have a game that hinges on an incoming reliever shutting down an inning, and you go to your best arms, and 8 out of 10 times those base runners come around to score anyway … it’s going to swing a lot of ball games out of your favor.

“We believe that this group will turn it around and once again be a weapon for us,” Twins GM Thad Levine said this weekend on the Inside Twins radio show.

I think that if Levine had stopped there he might have a lot of Twins fans angry with him as the GM of their favorite team. As one of the chief architects of the roster, to suggest that a weakness will simply become a strength without any action – that would irritate people who want more done to the roster than simply pointing out bad luck and shrugging. So his next point from his radio appearance on Inside Twins is critically important.

“I think we also have to own our side of that equation, which is more [pitches] in the middle of the strike zone that are more deemed to be hittable pitches. Certainly we can’t just keep doing the same thing and expect something different to happen. I think something slightly different will happen just from regression to the mean, but I think we have to take ownership of improving our pitch execution out of that group of men, because by and large we probably have seen also a higher percentage of pitches in the middle-middle part of the zone. … We need to put ourselves in a better position to succeed,” Levine said.

Exactly. Stats don’t regress themselves. When stats regress its a reflection of play on the field. It’s a combination of performance improvement and luck. Of course there’s a lot of variance involved in athletic performance, but if a team loses 100 games in a season and their starting staff has a 6.00 ERA, they weren’t merely the victim of 6 months of bad luck.

Let’s circle back on the stranding/not stranding runners. I think Rogers will be fine in this regard. He’s their best reliever and he’s been pretty good this year. I am wondering what’s going on with Tyler Duffey. And to be the second lefty in a bullpen with Rogers, Thielbar looks like he’ll be counted on in those medium leverage spots this year. After a good season last year, we haven’t seen good results so far this season, despite a 22:2 strikeout-to-walk ratio.


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