Ray is 1-3 with a 4.01 ERA in five starts for Reno this year. In 24 2/3 innings he has allowed 25 hits, walked 16 and struck out 35.
"He has pitches to strike guys out, he's got a lot of strikeouts down there and we just want to see what he's got, give him a shot," D-backs manager Chip Hale said. "We're playing a team in the Rockies who can really hit. We saw that at our place. But they swing at a lot of pitches, so his power stuff we think matches up good with them. We had the option of a few guys and a couple of them are lefties. Robbie just makes sense right now at this point."
Ray figures to get a couple of starts before Bradley is ready to return. The plan is for Bradley to throw a bullpen session Saturday and he could be ready to come back right when his 15-day stint on the DL is over.