Vizcaino struck out two and walked one in 1 2/3 scoreless innings on Saturday night, at least giving the Rockies a chance in their 5-3 loss to the Marlins.
On Saturday, Matt Herges threw a clean eighth inning, but it was just his seventh appearance in the team's past 19 games as he works through inconsistency. Jason Grilli has given up runs in his past three appearances. So manager Clint Hurdle said Vizcaino, signed to a two-year, $7.5 million contract, "has probably moved up."
Pitching in the finale on Sunday, Vizcaino continued to give his club strong support with his ninth scoreless outing in his past 10 appearances, striking out one in two-thirds of an inning in Colorado's 3-2 win over Florida.
Vizcaino struggled with arm troubles throughout the spring, went on the disabled list during the season's first week and didn't join the Rockies until June 7. The early performances were rough, but he has regained some of his form. Opponents have hit .222 off him since his return, and right-handed hitters are hitting just .143 this season.
"I think he's shown improvement with his fastball command the last two times out -- best velocity of the season, best command of the season," Hurdle said. "Coming off the bad outing in Pittsburgh [three runs, four hits in one inning], I thought he bounced back nicely. He had a number of good outings before that."
Hurdle said he hopes Herges took a step in the right direction on Saturday, but there are disturbing similarities between Herges and Grilli.
"[With] both of them, fastball command is an issue -- a major issue," Hurdle said. "Secondary pitches, commanding the strike zone, [is] not good. That's a bad combination when you're coming out of the bullpen."
Hurdle also said he informed left-hander Valerio De Los Santos, who has walked 11 in eight innings in two starts, that he will be sent down to Triple-A Colorado Springs on Monday.
Hurdle said he would like to add a relief pitcher. Righty Ryan Speier is not eligible, because he hasn't been at Colorado Springs for 10 days since he was optioned. The only way he can return before then is if there is an injury to a pitcher.
It could be a brief stint for the hurler, since the Rockies will activate left-handed starter Jeff Francis from the disabled list on Wednesday.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.