Rockies manager Walt Weiss said the number of left-handed hitters carried by the D-backs, whom the Rockies face in seven of the next 10 games, and Braves, who come to Denver Monday, figured in the decision. Outman, 1-0 with an 0.84 ERA in 10 2/3 innings over five games at Triple-A, can pitch in short or extended stints, much the way Volstad was slated to do, but his presence frees Weiss to use lefty Rex Brothers (1-0, 1.23 ERA) earlier in the game against a key lefty hitter.
"Our bullpen isn't necessarily designed for matchups exclusively, but with an extra lefty, that option is in play, as opposed to trying to save Brothers for later in the game, that eighth or ninth," Weiss said.
Outman went 1-0 with a 1.74 ERA in eight Spring Training games, but the Rockies felt Volstad showed excellent downward life on his pitches and Outman needed to improve that aspect. Also, Outman had four walks and six strikeouts in 10 1/3 innings. At Colorado Springs, Outman forced ground balls and had 14 strikeouts against four walks.
It's also a chance for Volstad, a starter until this season, to pitch regularly.
"Chris didn't perform poorly," Weiss said. "He's in a situation where he wasn't getting a lot of consistent work. Hopefully he'll go down there and get that consistent work. I imagine he'll be with again us at some point this year."
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. Owen Perkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.