Moscoso delivered 2 1/3 scoreless innings on Monday against the Mets, but his ERA stands at 7.53. He gave up eight earned runs in 1 2/3 innings on July 26 against the Nationals.
On Monday, Moscoso pitched in place of Josh Roenicke -- normally a member of Colorado's piggyback crew of extended relievers. Roenicke has logged 73 1/3 innings in 2012 -- more than his last three seasons combined -- and is being used in smaller doses to help rest his arm.
Manager Jim Tracy said Moscoso will rejoin the team as a September callup.
"We're very mindful of where [Roenicke] is at from an innings standpoint, which goes back to Moscoso and a lot of the reason as to why he'll return to our club in early September," Tracy said.