"We've got to be able to give Hanley a day here or there and get more out of him," Mattingly said.
Mattingly said Ramirez would not be moved to third base, which is his likely future position, because the club assured him he wouldn't be moved back and forth.
Rather, third base will be shared by Justin Turner and Chone Figgins while Uribe is out, which Mattingly hinted would be longer than the minimum 15 days.
"The last one [on the recent homestand], he missed seven days and you see what happened," Mattingly said of Uribe's initial injury. "Hamstrings are always messy. I've watched over the years and you've got to be careful, and it's hard to tell when the guy is fully healed."
Uribe wasn't, and now his sure glove and .303 batting average are likely out three to four weeks. Mattingly said he's satisfied with Ramirez's "effort and work" at shortstop, but it's no secret that Ramirez's bat is his calling card, not his glove.
"I don't feel we get a lack of effort in any way, shape or form," he said. "He is what he is."
Arruebarrena, a former Cuban teammate of Yasiel Puig who signed a five-year $25 million contract in February, is the opposite of Ramirez. He has a Major League-ready glove but a bat that Mattingly kindly described as "a work in progress." He is hitting .379 over his last seven games.
"He's going to pick it up," Mattingly said. "We simply feel he can catch it and cover. Those are the things we like most."
Uribe was injured in the ninth inning Tuesday night.
Also on Tuesday, Cuban infielder Alex Guerrero had a piece of his ear bitten off by teammate Miguel Olivo in a dugout fight. Mattingly said there was no discussion about whether Guerrero would have been called up instead of Arruebarrena if he had not been injured. Guerrero, who underwent plastic surgery, could be out a month.