"We saw a lot of positive things last year, like his baserunning and defense, but the one concern was the strikeout-to-walk ratio, which you can get away with if you're doing other things," said Twins manager Paul Molitor. "So it was a combination of the way he was swinging the bat and his plate discipline. Hopefully, he can go down there and recapture some of that stuff."
Rosario was also benched during the seventh inning of Wednesday's 6-3 loss to the Tigers after making several mistakes during the game. He missed the cutoff man in the first, let a blooper fall into short left field in the fifth and attempted to steal third base with two outs in the seventh with the Twins trailing by four runs and Joe Mauer at the plate.
Molitor said that Rosario will have to earn his playing time at Rochester, as the Red Wings already have Byron Buxton, Max Kepler and Adam Brett Walker in the outfield.
"He's going to have to get work fast," Molitor said. "I think he was taken a little bit aback, which is OK. In talking to him, you try to explain to him, praise him, critique him and encourage him. We'll see how he responds."
Grossman was signed by the Twins on Tuesday after he opted out of his Minor League contract with the Indians. Grossman was hitting .256/.366/.446 with six homers, five doubles and 14 RBIs in 35 games with the Indians' Triple-A affiliate in Columbus. He wasn't in Rochester's lineup on Wednesday; he heard about the callup during batting practice.
"I'm excited to be here and help in any way I can," Grossman said. "I'm excited to be a Twin and look forward to what's ahead."
Grossman, who played with the Astros from 2013 to 2015, is a career .240/.327/.341 hitter in 190 games. He's seen most of his defensive action in left field but also has experience in center and right.
"He's a guy with some experience," Molitor said. "You look at the positives. He takes good at-bats. He's a switch-hitter and probably a little bit better right-handed than vice versa. Not a burner, but he's an intelligent baserunner. He can play all three outfield positions, but center field, he's probably not an everyday guy and more of a spot defender out there."
Rhett Bollinger has covered the Twins for MLB.com since 2011. Read his blog, Bollinger Beat, follow him on Twitter @RhettBollinger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.