"Once I get too quick [in my delivery], the arm drops a little bit and it's hard for me to get on top of the ball," Duffey said. "I'm low, three-quarters to begin with, so once I start missing up, things start flattening out, it runs a little more than it sinks, things like that. The curveball gets a little more sideways versus up-and-down. That's when stuff gets hit."
According to Twins manager Paul Molitor, even Duffey's good breaking balls have been noticeably less effective this season, with hitters better able to foul them off and extend at-bats to wait for better pitches.
"I don't think he's tipping anything," Molitor said. "It's just their approach to him is pretty good. A lot of guys have made adjustments and he hasn't figured out how to counter. At least not yet."
Duffey's sophomore season has been a struggle after he showed so much promise last season, when he went 5-1 with a 3.10 ERA in 10 starts. In 2016, he has posted a 6.18 ERA through 11 starts, with nearly as many earned runs (41) as strikeouts (49).
Amid his recent tough stretch, Duffey, who is not afraid to show strong emotions on the mound, has almost been his own worst enemy by allowing himself to get too frustrated with his performance, according to Molitor.
"I've actually had conversations with multiple people, including [Molitor], about how having a fire is a good thing, but there's a right and a wrong way to do it, to the point where he is mentioning that I'm kind of wasting energy on being upset rather than putting that energy toward getting somebody out," Duffey said.
Molitor is not yet sure about whether he is going to stick with Duffey to make his next scheduled start and will have conversations with general manager Terry Ryan and his coaching staff over the next several days to come to a decision.
In the meantime, catcher Kurt Suzuki is confident that Duffey will be able to make those necessary second-year adjustments if given that opportunity.
"He's obviously not pitching up to his standards and how he would like," Suzuki said. "We all got to know [Duffey] and how good of a pitcher he is, and he's just in one of those ruts where nothing can really go right. I don't know if he's just not feeling good or whatnot, but he's a guy that competes out there."
This story was not subject to the approval of Major League Baseball or its clubs.