NEW YORK -- There's a lot of talk about how this American League Division Series is primed for an explosive battle between the two most powerful lineups in Major League history -- but don't sleep on the Yankees' and Twins' rock-solid bullpens, which might have some objections to all that bomba talk.
New York has all of the big names, of course. Give the Bronx Bombers a lead, and you'll be staring down the likes of Aroldis Chapman, Adam Ottavino, Zack Britton and Chad Green in the late innings. But don't be surprised if this weekend offers a coming-out party for unheralded Minnesota right-hander Tyler Duffey as one of the most dominant relievers on the field.
The Twins wouldn't be here had it not been for many surprises all around their roster. Mitch Garver becoming one of the best hitters in baseball comes to mind, as does the emergence of a handful of rookie pitchers who more than held down the fort in August and September. But Duffey's transformation into a bullpen monster might have surprised Twins Territory most of all.
"The second half of the year, I mean, how many guys can you really say have been better than him in all of the game?" manager Rocco Baldelli asked. "I wouldn’t say very many."
Check out some of Duffey's second-half numbers. His 42 percent strikeout rate was third in the AL to only Nick Anderson of the Rays and Liam Hendriks of the A's. His 1.53 ERA was fourth among qualified AL relievers, and at one point, he posted a stretch of 23 2/3 scoreless innings across 26 appearances from July 28 to Sept. 25 before he allowed a homer to Jorge Soler in his final outing of the regular season.
Strikeout rate minus walk rate in AL relief corps this season
1. Liam Hendricks, A’s, 32%
2. Ken Giles, Blue Jays, 31.7%
3. Emilio Pagan, Rays, 31.1%
4. Tyler Duffey, Twins, 28.6%
5. Ryan Pressly, Astros, 28.4%
And though his 0.00 ERA in 10 2/3 August innings was already impressive, Duffey might have been even better in September, when he struck out 22 batters without issuing a walk. He held opponents to a .167/.186/.286 slash line in the final month of the season.
"Everybody knew that it was in there," teammate Taylor Rogers said. "I think that kind of takes away the value of it, is because I kind of thought that that's what he always had in him. So I guess the shock value to me is a little lower than most people."
Rogers might have seen this coming, but how is it that Duffey, who posted a 5.42 ERA as a starter in his first two seasons and most recently posted a 7.20 ERA in three Major League stints last season, could break out in such spectacular fashion?
It started during the offseason, when new Minnesota pitching coach Wes Johnson and assistant pitching coach Jeremy Hefner visited Duffey at home in Houston and pitched the idea of Duffey, a sinkerballer throughout his career, instead relying more heavily on his four-seam fastball and big curveball to attack hitters.
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"I came in and they told me, 'Here's where you get swings and misses. Attack. Use these pitches as you need to and maybe dial back usage on some others, and in other counts,'" Duffey said.
The idea is relatively simple: Throw the four-seam fastball up and throw the curveball down so that the pitches "tunnel" more seamlessly out of his hand, making it difficult for hitters to tell which pitch is coming in any given count. Duffey's sinker and changeup have essentially been scrapped altogether.
It took a while for Duffey, who used to thrive on throwing the sinker down, to get comfortable with throwing his four-seamer up, and much of the work he tried to accomplish when he began the season in Triple-A Rochester was in developing a more natural feel for the top of the strike zone.
Ultimately, it came down to a few tweaks to get everything to click: First, gripping his four-seamer more tightly, with his fingers closer together, which added some velocity and some slight movement; and secondly, raising his arm angle slightly in his delivery to get more on top of the four-seam fastball, which he discovered one day in May while playing catch with Hefner and also had the side effect of tightening some of the horizontal break of his curveball.
"Now, it’s an active decision to go down in the zone, when you go down there," Duffey said. "Make me think about it for a half-second, make sure you get on top of it or whatever it may be. I’m just letting it ride. Ultimately, it’s being tentative, that’s when stuff doesn’t play up. You go out and attack guys, that’s how it works."
It's worked to the tune of a 2.50 ERA and 82 strikeouts in 57 2/3 innings this season. After being shuttled back and forth between Triple-A and the Majors three times last year, Duffey has finally found his niche as a late-inning guy and the Twins' "fireman" out of the bullpen.
"His ability to take everything that came to him early in the year -- which was not the easiest to deal with -- like spending time at Triple-A, all those difficulties and being able to put those aside and turning himself into one of the best relievers in baseball," Baldelli said. "I mean, that’s a heck of a story. He deserves all the credit for that."
Duffey is having a ton of fun now. He hopes that he -- and the rest of Minnesota's bullpen -- can have a good time surprising some people on the national stage.
"We play in Minnesota," Duffey said. "We don’t play in New York. We don’t play in L.A. So it’s just flying through the radar, and hopefully it stays that way. Then, we can shock some people and have some fun."
Do-Hyoung Park covers the Twins for MLB.com. Follow him on Twitter at @dohyoungpark and on Instagram at dohyoung.park.