"I almost hit Corey Hart in the head, and then he hit one off the right-center-field wall," Duffey said with a laugh.
But flash forward a year later, and Duffey is expected to be an important piece of the rotation this season. He made his Grapefruit League debut against the Red Sox on Thursday night, throwing 1 1/3 scoreless innings, but was removed after issuing a one-out walk on his 36th pitch of the game, which the Red Sox won, 6-5.
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It wasn't Duffey's best performance, but barring a catastrophic spring, he'll be part of the rotation, as Twins manager Paul Molitor has said it would take something "fairly significant" for Duffey to not be there. Duffey, though, isn't taking it for granted, as he's still approaching this spring as if he's competing for a spot in the rotation.
"I've said all along I have to go out and pitch, and pitch well," Duffey said. "If I do that, it takes all the guess work out of it. As long as I do my job that I'm capable of doing, everything will take care of itself."
Duffey, 25, had a strong showing down the stretch last year, going 5-1 with a 3.10 ERA in 10 starts after being called up from Triple-A. Duffey was even better when you throw out his shaky debut in Toronto, as he went 5-0 with a 2.25 ERA in his final nine outings.
"With what he did for us down the stretch, he's put himself in a good position," general manager Terry Ryan said. "Without just handing things over, he's put himself in a good spot. He did everything you'd hope for in those 10 starts. He's in a good spot. There's no doubt about that."
Duffey had all that success throwing just his four-seam fastball, two-seamer and curveball, as he ditched his changeup after serving up a homer to Jose Bautista in his debut. But under the guidance of pitching coach Neil Allen, Duffey is looking to incorporate his changeup more this year, and threw it four times on Thursday.
Duffey said it's more of a split-change that ranges from 80-84 mph, and it's a pitch he used roughly 10 percent of the time in the Minors, so it's not too much of a change to bring it back into his arsenal in the Majors.
"Hopefully I can add that in and have it be a reliable pitch for me," Duffey said. "I've been picking [Allen's] brain a lot. And I've been talking to Ervin [Santana] because we have similar grips. So I have plenty of guys to ask about it and plenty of help."
Duffey also had to ask other players about the best way to prepare this offseason for the upcoming season, as he had never pitched deep into September and October before. He saw a big jump in his workload, as he went from throwing 149 1/3 innings in 2014 to a career-high 196 innings between the Minors and Majors in '15
But Duffey said he found an offseason plan that worked for him, training in Houston with several fellow big leaguers such as St. Louis' Jaime Garcia and Pittsburgh's Mark Melancon, and didn't start throwing again until January to give his arm some rest.
Duffey said he feels strong this spring, and the Twins have said they don't plan on having any restrictions on him this season.
"I'm not overly concerned about it," Molitor said. "He's affirmed to everybody, training staff and everyone else, that he feels great. There's been no carryover from the fact he threw close to 200 innings."