Twins' new starter search down to Gibson, Deduno and Walters

ATLANTA – After six weeks with a stable, if struggling starting rotation, the Twins decided to make a change Monday. But they're not ready yet to reveal who is taking Pedro Hernandez's place.

Former first-round pick Kyle Gibson, who took a no-hitter into the eighth inning against Lehigh Valley on Sunday, would be on normal rest should the Twins decide he's ready to make his major-league debut in Detroit on Friday, when Hernandez's turn comes up again. But "we have options, and we'll decide that [later]," manager Ron Gardenhire said. "We have a few guys throwing the ball very well down there."

Hernandez wasn't throwing it well enough in the majors, the Twins concluded after giving up three runs in four innings against Boston on Sunday. So the Venezuelan lefthander was returned to Class AAA Rochester shortly after the Twins arrived in Atlanta.

"There were a lot of two-strike base hits against him [Sunday]. That says he needs a put-away pitch," Gardenhire said. "He needs a pitch that can finish a hitter off."

With Minnesota's bullpen overworked — Kevin Correia on Monday became the third consecutive Twins starter to fail to complete five innings — the Twins chose to call up lefthander Caleb Thielbar, a native of Randolph, Minn., to give Gardenhire an eight-man bullpen for use during this three-game series with no designated hitter. One member of the bullpen will likely head to Rochester on Friday, when the roster spot goes to the team's new fifth starter.

So who might that be? Under baseball rules, it can't be Hernandez or Cole De Vries, because players sent down must remain in the minors for 10 days; De Vries was optioned on Saturday. And Liam Hendriks, who opened the season in the Twins' rotation, in on the Red Wings' disabled list because of a sore right elbow.

Gardenhire hinted there are three likely candidates: Samuel Deduno, P.J. Walters — and Gibson.

Walters, who is 4-0 with a 2.08 ERA in his past six starts, and Deduno would have to be added to the Twins' 40-man roster in order to be called up.

Thielbar became the 29th native Minnesotan to ever play for the Twins, but he has an even more remarkable local distinction: He's the first former St. Paul Saint to ever play for the major-league team across town.

Thielbar rocketed through the Twins' minor-league system in only 21 months, signing with the Twins on Aug. 18, 2011, after spending the summer with the Saints. He had not allowed a run in his past eight outings for Rochester, a streak of 11⅓ innings.

"Throwing the ball very, very well," Gardenhire said. "They've been watching him pretty close. He's put together a nice string here, not giving up too much of anything."

Thielbar, drafted by the Brewers in 2009 after playing for South Dakota State, was informed of his promotion Monday and flew to Atlanta, where he arrived shortly after the game had begun.