CHICAGO — Off to a highly disappointing start, the last-place Twins initiated a flurry of moves on Thursday by placing pitchers Tommy Milone and Casey Fien on waivers, according to two sources with direct knowledge.

In addition, a separate source said one of the two newly opened 40-man roster spots will be used to add Triple-A Rochester catcher Juan Centeno, who figures to replace slumping backup catcher John Ryan Murphy on the big-league club.

Milone, 29, was recently dropped from the Twins’ rotation after a slow start. After winning the No. 4 slot in the rotation, the finesse left-hander has posted a 5.79 earned-run average in five outings.

Acquired from the Oakland A’s in a July 31, 2014, deal for outfielder Sam Fuld, Milone failed to complete five innings in three of his four starts.He went 9-5 with a 3.92 ERA last season.

Fien, 32, has a 7.90 ERA in 14 relief outings this season. After filling a primary setup role for much of the 2013-15 seasons, he had been downgraded to middle or even long relief.

Because Fien was outrighted previously (2010), he would have the right to reject an assignment to the minor leagues should he clear waivers. Milone, who has never been outrighted, would not.

Milone is guaranteed $4.5 million this season after going through the arbitration system again this offseason. Fien is guaranteed $2.275 million and, like Milone, could be eligible for arbitration two more times before reaching free agency.

Centeno, 26, was signed as a minor league free agent this offseason after brief big-league stints with the Milwaukee Brewers and New York Mets. A left-handed batter, he impressed Twins manager Paul Molitor this spring with his strong defensive skills, throwing ability and slashing approach at the plate.

Centeno was hitting just .245, but his on-base percentage for the Red Wings was .315 and he had struck out just four times in 49 at-bats. He homered Tuesday for the first time this season.

In 61 big-league at-bats over the past three seasons, Centeno has hit just .164.

Murphy, set to turn 25 on May 13, was acquired from the New York Yankees in a November trade that cost the Twins former first-round pick Aaron Hicks. Both players have struggled mightily at the plate through the season’s first month, with Murphy hitting .075 (3 for 40).

Murphy’s .119 OBP easily ranked last among 305 major leaguers with at least 40 plate appearances.

He was ejected from Monday’s game while arguing on behalf of rookie right-hander Jose Berrios, and Murphy also had an exchange with plate umpire Scott Barry during Wednesday’s 16-4 blowout loss that may have led to the dual ejections of Molitor and reliever Ryan Pressly.

The Twins needed to clear a 25-man roster spot in advance of Ervin Santana’s return from the 15-day disabled list on Saturday, when he is scheduled to start the middle game of a three-game series against the Chicago White Sox. In addition, No. 2 starter Kyle Gibson (shoulder) is making progress and could return as soon as next week.