Three key Twins relief pitchers: Why have they struggled so badly?

Twins observers had reasons to be concerned about the team's bullpen going into the season after watching several established pitchers from 2020 — guys like Trevor May, Sergio Romo and Tyler Clippard — depart.

But to be fair, the Twins also had a reason to be optimistic that their plan heading into the year could work: a bullpen anchored by Taylor Rogers and veteran Alexander Colome on the back end, with bridges built the likes of Tyler Duffey, Hansel Robles and Cody Stashak. Hard-throwing Jorge Alcala could build up equity in lower-leverage situations. Caleb Thielbar would thrive in situational matchups. And Randy Dobnak could eat innings if a starter had a short outing.

Rogers is established. Colome was coming off of a short year with a 0.81 ERA and longer stints with ERAs under 3.00 the two years before that. Duffey posted a 2.31 ERA over 80 appearances in 2019 and 2020. Stashak looked to be a decent medium-leverage option based on his work in 2019 and 2020. Robles was solid for the Angels in 2018 and 2019. Alcala has electric stuff.

So it's not like the plan was entirely half-baked or based merely on wishes.

That said, it felt even before the season started like the Twins were one arm short. And that has been magnified — as these things are — as their best-laid plans have fallen apart in a few cases.

In particular, Colome, Stashak and Duffey have underperformed based on expectations. The following is an examination of why that is, exactly.

In short: Duffey, after remaking himself into a breaking ball pitcher in 2020 with great success, has found negative results with a similar pitch mix in 2021. Stashak, too, has become more of a breaking ball pitcher than fastball pitcher. Both are getting behind in counts, walking more hitters and suffering the consequences.

Colome's velocity and pitch mix have been fine relative to past seasons, but his command has been dismal — and magnified by the high-leverage situations in which he has failed.

All three struggles are a function of a reliance on breaking balls, which seems to be a principle of the Twins' pitching belief system.

When it works, it's great: a higher strikeout rate without all the expensive velocity. But when it doesn't work, it shows up in two ways: poor control that leads to walks and/or falling behind in counts; and poor command, which leads to fat pitches that get crushed.

Let's take a closer look:

Colome

FanGraphs shows that his fastball velocity is similar to what it was last year and his cutter velocity is the same. But StatCast data shows that 61.5% of balls put in play off Colome have been "hard hit," way over his career average of 36.6%.

Generally, it's been poor command of his cutter that has done him in:

In blowing a save on Opening Day, he was undone by his own throwing error but also two hard hits off of cutters left over the plate. On April 10, he allowed the go-ahead single to Seattle on another cutter over the plate. The next day, his hanging cutter to Kyle Seager was pounded for a three-run homer in the ninth in an 8-6 loss. Here's that one:

A similar hanging cutter was the culprit on a 10th-inning homer in a loss to Cleveland on April 26, while two other outings were spoiled by poor control.

That might actually be encouraging for the Twins. If Colome can regain command of that pitch, he can turn his season around. But if he keeps hanging it over the plate, his cutter is merely a batting practice fastball and Rogers will need to record six-out saves for this season to have any hope.

Duffey

In 2019, as Duffey emerged as a solid reliever, 54% of his pitchers were fastballs and 46% curves — a mix that helped keep hitters guessing while helping him stay ahead in the count.

That mix shifted in 2020 with strong results: Duffey threw 44% fastballs and 56% curves, but he thrived on getting batters to chase his curve out of the zone (batters swung at a whopping 40.3% of Duffey offerings outside the zone in 2020) and he posted a 1.88 ERA.

But 2020 also showed one disturbing trend: his average fastball velocity dipped from 94 mph in 2019 to 92.7 mph in 2020.

That dip in velocity has continued this season (92.8), but batters are no longer chasing his curve (27.2% swing rate outside the strike zone). And he's throwing even more breaking balls this season: 40% fastballs, 60% curves.

His walk rate is three times as high as last year and he's already issued nine free passes in just 11.1 innings.

Two walks and a wild pitch spoiled an outing on April 14 vs. Boston. He allowed a homer in Cleveland on April 26 on a 3-2 curve after falling behind 3-0.

On Thursday in a loss to Texas, Duffey allowed a wild pitch on a curve to get the free runner to 3rd base in top of 10th, then fell behind 2-1 on three curves before allowing the go-ahead single on a fastball. And Saturday in Detroit, Duffey allowed two hits (both on curves), a walk (three of the four balls were curves) and a wild pitch.

To be fair, Duffey's struggles have been a little more isolated. But his ERA ballooned to 5.56 after that game in Detroit, and control issues with breaking balls have been at the heart of games in which he has struggled.

Stashak

This is the most interesting case because it seems like he's been entirely reinvented in an attempt to go from solid to more than that — and instead has regressed badly.

He walked just four batters in 40 innings spanning 2019 and 2020 while striking out 42. That's a recipe for success, which Stashak found by posting ERAs of 3.00 and 3.24.

Stashak threw fastballs about 55% of the time each of those years, with sliders accounting for about 40% with an occasional changeup mixed in. This season? He's thrown fastballs 40.5% of the time and sliders 56.4% of the time, a complete flipping of the script.

He's striking out a lot more hitters — 19 in just 10.2 innings. But his walk rate is waaaaaayyy up, with seven already this year after just those four the past two years combined.

And hitters are doing damage when he falls behind in counts against both pitches — with a fastball that has dipped in velocity from 92 mph last year to 90.9 mph this year on average.

Against the Brewers on April 4, Stashak gave up a homer on a 3-1 pitch. In a 4-3 loss to Detroit on April 6, he recorded strikeouts for all three of his outs — but he also gave up three hits and a walk, with the major damage done on a double off a 3-1 count.

Against Pittsburgh on April 25, Stashak gave up three runs on three hits — with all three hits coming on sliders.

And in Friday's outing, which earned him a demotion to Class AAA St. Paul, Stashak gave up a single on a 2-1 pitch, a walk and a three-run homer on a 1-0 pitch.

Long story short: The Twins lack power arms in the bullpen, and to compensate they are asking their pitchers to miss bats with breaking balls. They're getting 9.8 strikeouts per nine innings from their relievers. But they are also giving up a lot of base runners (1.38 walks and hits per inning pitched, No. 21 among MLB bullpens).

Add it up and Twins relievers have a 1-11 record — two more losses than any other bullpen in MLB — and a 4.92 ERA, tied for No. 25 in baseball.

Whether the problem is approach or execution is a question for another day.