FORT MYERS, Fla. – Tyler Duffey came to Twins camp with a plan: practice throwing changeups, a pitch that hasn't been too useful in his brief career. And he accomplished his goal, frequently offering hitters his third-best pitch in situations where his nasty curveball might have worked better.

On Tuesday, Duffey realized the flaw in his blueprint. He forgot to get his other pitches ready for the season.

Duffey was optioned to Class AAA Rochester as the Twins reached the 25-man roster limit, ending with a resounding thud a camp he had hoped would be a simple checkpoint toward the Twins' 2016 rotation.

Ricky Nolasco, hoping to salvage a comeback season after two injury-filled years, will be the Twins' fifth starter and make his season debut April 9 in Kansas City.

"I came in thinking, or at least hearing, that I was No. 4 [in the rotation], so I worked on stuff and didn't get ready to go," said Duffey, who "fully expected" the news manager Paul Molitor delivered Tuesday morning. "That showed in the last two outings, when I needed to execute, and I didn't have that. … I've been through it now. Now I know the ropes for next time around."

Next time won't be long, Molitor figures, if Duffey recovers the form that helped him go 5-0 with a 2.25 ERA in nine starts from Aug. 15 on last summer.

"We rode this thing as long as we could," said Molitor, who earlier in the month said it was "difficult to picture" Duffey not being in the rotation. "Some of the other things weren't as consistent as we'd like to see. He's going to try to go make sure he gets back on track quickly, so when we dip down [for a starter], he's a guy we look at."

Molitor and pitching coach Neil Allen told Duffey that "the changeup is still an important component for him," Molitor said, "but he knows that to get swings on his curveball, he has to do better with his fastball."

Duffey posted a 7.30 ERA in four starts against major league teams, and was knocked around by a Class AAA team last week, too.

"I know that I didn't pitch well, plain and simple," he said. "Had I thrown like I did last year, I don't think it would have been an issue at all, but I didn't do that. So now I'm here. I've just got to go and pitch well."

He'll be joined by Tuesday's three other roster casualties, a trio of relief pitchers who mostly pitched well but couldn't lock down a spot. Lefthander Ryan O'Rourke was optioned to Rochester, and lefty Logan Darnell and righthander Brandon Kintzler were assigned to minor league camp.

"I thought I pitched well enough to make the team," said O'Rourke, who posted a 1.35 ERA in eight spring games, "but obviously, I didn't."

It was more about how the pieces fit together, Molitor said. By making those cuts, he completed the Twins' bullpen, with lefthander Fernando Abad and righthanders Michael Tonkin and Ryan Pressly earning the final spots.

"I have high hopes for Pressly. I thought his chances were pretty good, and he pitched well. He earned it," Molitor said of the reliever, who struck out 10 in 10 innings with a 1.80 ERA. "Fernando, he kind of grows on you — his ability to throw it over, to get lefties and righties out."

Molitor also informed Nolasco, who had a good but not great spring, that he will be in the rotation once more. His reaction? "He simply said, 'I'm ready,' " Molitor said.