DENVER -- Rockies right-handed pitcher Jhoulys Chacin and third baseman Chris Nelson are going through the hard lessons of learning the difference between pain and injury.

Chacin was 0-3 with a 7.30 ERA in five starts and facing a demotion to Triple-A Colorado Springs when he underwent an MRI and it was learned that the weakness and soreness in his right arm that had lingered since Spring Training was a combination of biceps tendinitis and shoulder inflammation, which threatens his rotator cuff. The Rockies put him on the 15-day disabled list May 6, and aren't letting him throw until he regains strength in the shoulder.

Nelson has suffered with pain in his left wrist since April 25 when he dove to field a ball in Pittsburgh. It never really improved. Now Nelson is undergoing treatments, and when he returns he'll be trying to improve an average that stands at .219.

The principle sounds simple: play with pain, but not with injury. But figuring out where the line is can be difficult.

Chacin, whose first full season was last year, and Nelson, who made the Opening Day roster for the first time this season, have suffered not only from pain but from a lack of understanding of exactly how much they were limited by their injures. There's also the player's natural urge to play through pain.

"I knew my arm wasn't good, but I was trying to pitch through it," Chacin said. "I'd never been on the DL before, even in the Minors. I've been sore before, but this was something different. I was really weak in my rotator cuff.

"I have to get strong in the rotator cuff. If I didn't do that, it could get worse and maybe I'd have to have surgery."

Nelson battled various injuries throughout his Minor League career, and often was criticized for the repeated injuries. In his first real opportunity in the Majors, human nature took over and led him to not admit how hurt he was. The final straw might have been a diving play he made Sunday in Los Angeles.

"You don't want to be on the disabled list," Nelson said. "It's nothing you want to be proud of.

"But at the same time, I'm not really helping my team or helping myself. I just need to get it back healthy. Especially hitting with my wrist, and diving and all that good stuff, this is a learning experience."

Manager Jim Tracy said especially with Chacin, he asked him if he was hurt and had athletic trainer Keith Dugger keep a close eye on him. The problem, Tracy said, is it often has to come down to the player and the knowledge of his body, which isn't always there with an inexperienced player. Tracy admitted the club needs to be more proactive with inexperienced players.

"It's not a bad thing; it's understandable," Tracy said. "A young player at times is not going to be as forthright. You have to keep forcing the issue. You want honesty.

"There are a ton of athletes during the course of the season that play through soreness, get through stiffness. But pain is a completely different thing."

Moyer becomes oldest player to drive in run

DENVER -- Rockies pitcher Jamie Moyer erased an old teammate from the record books on Wednesday night.

By driving in two runs in a 6-1 victory over the D-backs, Moyer became the oldest player ever to drive in a run. At 49 and 180 days he broke the record of Julio Franco, a longtime big leaguer who was 155 days younger when he knocked in the last of his 1,194 RBIs.

Moyer got a kick out of learning he broke the record of Franco, a teammate of his with the Rangers in 1989.

"I'm not in this game to be breaking offensive records," Moyer said with a smile. "If you're around this long enough, things are going to happen like that."

The occasion gave Moyer a chance to recall Franco, who hit for both average and power.

"He covered the plate well, at times he used a really big bat, and he really understood himself, and he understood the strike zone," Moyer said. "Look at the good hitters, the guys that hit for average or drive in high runs year after year, they have a really good idea of what they're hitting and what they're facing on the mound on a given day.

"A lot of that comes with experience. You see a lot of people come into this game with a lot of talent, but those who are able to fine-tune create consistency throughout their careers. He had a long career."

Pacheco finding groove at the plate

DENVER -- Rockies third baseman Jordan Pacheco is quietly returning to the type of hitting that excited the club during Spring Training, as well as a late-season callup in 2011.

Pacheco hit .200 in sparing playing time early in the season before being sent down to Triple-A Colorado Springs. Pacheco hit .433 for the Sky Sox, and with Chris Nelson on the disabled list with a wrist injury he seems to be finding his Major League form with regular playing time.

Pacheco went 3-for-7 with a double and two RBIs in two games leading into Thursday's finale of two with the D-backs. The Rockies moved Pacheco into the No. 2 spot in the order for Thursday.

"It's all about your approach, and you have to develop it to hit at this level," Pacheco said. "Anytime you're on the field it's a good opportunity. We need 'Nellie' back, and we hope he gets back soon. All we've got to do is do what's necessary to win ballgames."

Manager Jim Tracy said he likes the control Pacheco is exhibiting during his at-bats. Wednesday, his RBI single was a simple swing that put the ball between the third baseman and the shortstop.

"This guy is a good hitter," Tracy said. "I didn't say he's a slugger or anything like that. He's going to give you a good, competitive at-bat. He's a good situational hitter. He's a bat-to-ball guy, not a huge strikeout guy."

Pacheco is a work in progress at third base. An infielder in college at the University of New Mexico, the Rockies converted him to catcher in the Minors, then added third base and first base in an effort to give him more playing opportunities. When the Rockies sent him down in April, the plan was for him to become more comfortable at third.

"We're not asking him to be Brooks Robinson," Tracy said. "But his decision-making on balls off the bat has improved."

Guthrie aims to keep up with fellow starters

DENVER -- The Rockies acquired right-hander Jeremy Guthrie to serve as an innings-eating example for younger pitchers on the staff.

In recent games the staff did quite well while Guthrie was on the disabled list with a sprained right shoulder. Now Guthrie wants to keep up with the others.

Guthrie returned from the disabled list on Tuesday in San Francisco, and was effective if not lengthy. He held the Giants to one unearned run and four hits in 5 1/3 innings, but left after 90 pitches. The Rockies won, but blew Guthrie's lead, so he ended up with a no-decision.

Guthrie said he is recovering well between starts and expects to give the team greater length on Sunday when he faces the Mariners at Coors Field.

"I didn't feel any different from any other start; I felt pretty strong, even at the end," Guthrie said of his work against the Giants, when he struck out four and walked four. "I felt pretty normal other than being a little rusty at the start, facing Major League hitters. I wasn't able to get into the strike zone.

Juan Nicasio, in what he hopes is his first full big league season, has been the team's best pitcher. Recent callup Christian Friedrich has had two impressive outings. Alex White has been effective for all but one inning in two outings since he was called up from Triple-A. Jamie Moyer ended a run of short and ineffective starts with a win against the D-backs on Wednesday night.

"It was tough not to be there for the team, especially when we struggled," Guthrie said. "We're trying to get the pitching staff more consistently better. It's good to be a part of it. Hopefully, I can go out there, work deeper into games and have everybody feed off each other."