DENVER -- Rockies shortstop Troy Tulowitzki took batting practice at Coors Field on Sunday, and is pushing to begin a Minor League rehab assignment on Wednesday and return to the club in Detroit on Friday -- the first day he is eligible to come off of the 15-day disabled list.

Tulowitzki, who has not played since May 30 because of a left-groin strain, said he will come to Coors Field on Monday, with the team off, and take some swings and undergo further treatment.

He said "I'm going to push" to return on Friday, but the team's medical staff is being cautious, making sure Tulowitzki takes his comeback steps in the proper order so that they can lessen the possibility of him re-injuring himself.

Moscoso helping Rockies any way he can

DENVER -- It was hard for fans to be excited about Rockies right-handed pitcher Guillermo Moscoso's last two outings, but that's not his fault.

Moscoso threw 80 pitches in four innings of a 10-0 loss to the D-backs on Wednesday, and 2 2/3 more bullpen-saving frames of Saturday's 11-5 loss to the Angels. He allowed five runs in those lopsided games, but has shown signs of correcting some of the problems that arose in two starts earlier this season.

The Rockies called him up in late April, but he gave up 12 runs, walked four and yielded 16 hits in 9 1/3 innings in starts against the Mets and the Braves. Those games ended up close losses that could have been wins had Moscoso pitched better. The performances earned him a demotion to Triple-A Colorado Springs.

Moscoso, 28, would like to develop into a big league starter. He started in 21 of his 34 appearances with the Rangers and Athletics from 2009-11 before the Rockies acquired him from Oakland last winter. His career ERA was 3.47 entering this season. The long relief work is giving him a chance to clean up some bad habits in lopsided games, and be ready if the Rockies call upon him again, as either a starter or in a close game.

"When I first came up here, I was struggling with my command and working behind," Moscoso said. "Now I'm getting ahead in the last couple of outings. The other team had scored a lot of runs, and my job was to keep the team in the game.

"Our team is in a tough situation, trying to get back on track. My job is to help my team as much as I can, whether it's out of the bullpen or as a starter. I've been a starter all my career, but if my future calls on me to pitch out of the bullpen, I'll do it. You never know."

Moscoso would love to pitch in a game when the Rockies are winning, and he's hoping to do so when the Athletics come to town Tuesday through Thursday.

"I know those guys, and that'll give me more confidence," Moscoso said. "Plus I can help my teammates in the bullpen. We're always talking in the bullpen about how we'll pitch certain guys, so I can be a positive person for us."

Pomeranz, Chatwood having growing pains

DENVER -- Not only are the Rockies' starting pitchers struggling, but two key young arms are going through their growing pains in Triple-A Colorado Springs as well.

Left-hander Drew Pomeranz, who was in the early-season starting rotation, has issued 10 walks in his last two starts, which covered 10 1/3 innings. He has yielded just one run, but Major League lineups are not so forgiving. Right-hander Tyler Chatwood, who started the year in the Rockies' bullpen, suffered a chest-muscle injury after being sent down, and is 0-2 with a 6.26 ERA, with 15 strikeouts and 11 walks.

Manager Jim Tracy said they have significant enough issues that it makes no sense to have them in the Majors, no matter how much the Rockies' staff is struggling.

"They're still working on it," Tracy said. "Even though it was just three innings, I was sitting in the ballpark [Thursday] at Security Service Field. Prior to that game, being suspended because of all that weather that was in the area, I saw Tyler Chatwood pitch three innings. I saw some things that, for me, they need to continue to be worked on.

"I still saw the fastball being sprayed around. If you bring that to the big leagues, you're going to go further backwards before you can go forward. In the case of Drew Pomeranz, we're working on cleaning up a delivery, and the walks ... What purpose would that serve?"

Nelson turning heads with improved play

DENVER -- Rockies infielder Chris Nelson is demonstrating why he earned an Opening Day start this season.

Nelson began the year as the Rockies' third baseman, but suffered a left-wrist injury in late April, and found himself hitting .219 through May 14 before the Rockies placed him on the 15-day disabled list. Between his June 1 return and Sunday's start against the Angels, Nelson -- now stationed at second base -- he hit 4-for-10 (.400) with two home runs.

"My biggest problem before was my wrist hurt; now that it feels good, this is where I need to be," Nelson said.

The way Nelson struggled through pain made it easy to forget that he finished last year strong, and turned in some of the team's best at-bats this spring while earning a starting job.

"Case in point was the home run he hit yesterday [off the Angels' Dan Haren] -- a line drive that kept right on carrying," Rockies manager Jim Tracy said. "There's more bat speed. It's evident. There were things going on with that wrist that needed to be taken care of."

In Nelson's absence, rookie Jordan Pacheco put up strong numbers (.291 going into Sunday) as the third baseman. Nelson realizes he might have to be patient before he gets another run at playing time.

"That's the way it happens," Nelson said. "You've just got to come back and find out where you fit in. It's not an issue with me at all."