MINNEAPOLIS -- Twins manager Ron Gardenhire wants to see more consistency from rookie reliever Michael Tonkin, who has struggled in recent outings.
Tonkin, who remains one of the club's top relief prospects, has a 6.35 ERA in 14 appearances, with eight strikeouts and six walks in 11 1/3 innings. He's given up eight runs (six earned) in 2 2/3 innings over his last three appearances, including back-to-back subpar showings against the Red Sox on Tuesday and Wednesday.
Gardenhire said he wants to see Tonkin mix in more sliders, as he's throwing his fastball, that has averaged 92.7 mph, 80.1 percent of the time.
"He's overthrowing the baseball," Gardenhire said. "He's not throwing the breaking ball. You have to go out and tell him to spin the ball a little bit. You shouldn't have to tell him, but when he's not overthrowing his fastball and using his slider, he can get people out. But he's just trying to throw the ball through a brick wall right now and it's not working."
Twins assistant general manager Rob Antony agreed with Gardenhire, as he'd like to see Tonkin use his slider more to get hitters off his fastball.
"He's struggled the last few times out," Antony said. "He's trying to throw his breaking ball more, but has struggled recently after starting out well. I don't think he can just live on a fastball up here. He doesn't throw 98 mph. He's at 91 to 94-95 right now, and you have to something to take them off that baseball."
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. This story was not subject to the approval of Major League Baseball or its clubs.