ARLINGTON -- The Rockies asked backup catcher Wil Nieves to improve his situational hitting when they sent him to Triple-A Colorado Springs to start the season. Nieves entered his rare start Saturday with a .333 batting average in limited playing time since being called up May 25.

Asked how Nieves -- who started Saturday against the Rangers as Wilin Rosario rested -- has done with the specific points that come with batting low in the order, Rockies manager Jim Tracy said, "He's conscious of them. When you're getting a start once every four days, any measure of offensive consistency is a little bit of a stretch to expect it to be perfect."

But the main job of Nieves -- who has played in the Majors for the Yankees, Nationals, Brewers and Rockies -- is to take over for the injured Ramon Hernandez in helping Rosario, a rookie, learn the mental game, as well as help some of the Rockies' younger pitchers.

"Wil Nieves is in the big leagues and has been in the big leagues not because of anybody sitting around on a day-in, day-out basis and raving about his offensive prowess," Tracy said. "It's moreso his capability of taking a pitcher with whatever he has on a given day and trying to get that out of him."

Pomeranz making improvements at Triple-A

ARLINGTON -- How long the Rockies' four-man rotation lasts could be connected to the time it takes for left-hander Drew Pomeranz to show Major League consistency at Triple-A Colorado Springs.

Right now, the Rockies are hoping Pomeranz's good outing in his last start -- no runs or hits in six innings, with eight strikeouts and three walks in a victory over Salt Lake City -- becomes a trend. Pomeranz will start for the Sky Sox on Sunday at home against Tacoma.

"He had a good outing the last time out," Rockies manager Jim Tracy said. "Actually, the last couple that he's had have been much improved. But that was the goal when we sent him out -- to try to get him to that point. He's reaching for that, and you're hopeful that it continues."

The start against Salt Lake marked the first time in a month that either his hit total or his walk total was not alarming. Pomeranz still has managed a 3-4 record and 2.38 ERA in nine total Triple-A starts. But the Rockies have made it clear they expect Pomeranz to come back showing signs that he will grow into a front-of-the-rotation arm. Pomeranz was selected by the Indians fifth overall in the 2010 First-Year Player Draft and came to the Rockies for their former ace, Ubaldo Jimenez.

The Rockies are on their second turn in a four-man rotation, with a 75-pitch limit per outing, that has the appearances of being a teaching tool for pitchers currently on the staff. What isn't clear is whether the Rockies will put Pomeranz on a similar program when he returns or if the team will go back to a conventional five-man rotation.

"If he continues to force your hand in that regard, it'll create an interesting conversation," Tracy said. "Where should we go with this? Is he ready? Is he ready to come up here, and is he capable of being as consistent at this level as he's been in his last couple of outings at Triple-A?

"He must be capable of being a consistent strike-thrower. Is he capable of coming up here and commanding his pitches, and not walking three or four or five guys?"

Moscoso thriving in long-relief role for Rockies

ARLINGTON -- Rockies right-hander Guillermo Moscoso struck out four in two innings during Friday night's 4-1 loss to the Rangers, and he has not given up a run in his last four relief appearances entering Saturday.

Moscoso has a 6.20 ERA in eight total appearances, but much of that damage was done in two starts. He has responded well to a long-relief role. Moscoso has 23 Major League starts, including 21 with the Athletics last season.

"I'm a starter, but I've been throwing the ball well," Moscoso said. "I'm giving my team a chance to stay in the game. When you start a routine, when you start doing it right, you want to stay there. For now, I'm doing my job and helping my team."

Manager Jim Tracy said he sees a more comfortable pitcher.

"Maybe he's beginning to settle in," Tracy said. "Maybe it has taken this much time. Maybe he gets traded and feels as though he's into another proving ground. In his last couple or three outings, he has pounded the strike zone, and pounded it really, really well with his fastball."