WASHINGTON -- The heartwarming comeback of pitcher Juan Nicasio has become a story of knee-aching frustration. Nicasio will undergo arthroscopic surgery on July 16 to remove a "floating body" from his left knee, the Rockies announced Friday.

Nicasio (2-3, 5.28 ERA in 11 starts) has not pitched since suffering a left knee strain June 2 while trying to field a hard-hit ball back through the pitcher's mound against the Dodgers. Twice since then he has had fluid drained from the knee, the latest time being Wednesday night.

Last August, Nicasio was hit in the head by a line drive from the Nationals' Ian Desmond and suffered a broken neck when he tumbled to the mound. Against expectations, Nicasio made the season-opening starting rotation. However, early-season struggles and the injury have interrupted his inspiring story.

When Nicasio will return is uncertain. Manager Jim Tracy said much depends on whether doctors discover other damage during surgery.

"Once they get in there and remove that body and he gets through the recovery period, we'll start moving in the direction of trying to get him back to the mound between now and season's end," Tracy said.

The development of a new injury just as he thought he was close to a return left Nicasio frustrated.

"When I'm throwing, I feel good," Nicasio said. "But the doctor said [surgery is] better because I don't want to hurt my shoulder [by changing motions] or my leg.

"I don't want to say it's easy, but I know I'll be able to come back. But I came back from my neck. I'm not happy because it's a lot of things for me, but I still thank God for everything."

Giambi filling mentor role for Rox very nicely

WASHINGTON -- Veteran Jason Giambi joined the Rockies in 2009 to help with a late-season playoff push, as a pinch-hitter and as a veteran advisor and sounding board, and he's kept coming back for that reason. He didn't sign up for this year's 31-51 record going into Friday night's game against the Nationals.

Giambi, 41, still is upholding his end of the bargain. Several of the younger players making an impact this season regularly turn to Giambi for advice on situational baseball.

"I do what I'm supposed to do," Giambi said. "Would I love to win? Yes. Who doesn't love to win? But at the same time, I've done my job, gotten some pinch-hits. I've helped Chris Nelson out, helped Jordan Pacheco out, helped Tyler Colvin out, Carlos Gonzalez when he needs some hitting advice, Wilin Rosario and I have talked.

"That's what I'm here for. The record doesn't reflect on what my job is or what my role here is. I put in just as much work now as if we were 80-20 or 81-0. That would be in a perfect world, but there are things I can do to help these young kids speed up their learning curves and work with them on their swing and their approaches, and work with them mentally."

Before the Rockies put together winning seasons a few years back, one criticism was young players were more intent on merely proving they belonged in the Majors than learning how they fit on a winning club. The players that stuck, however, followed Todd Helton's quiet leadership, and eventually wins came.

Giambi has been vocal about avoiding that approach or developing any losing mentality, which would lengthen the development process. Missed opportunities to move runners, or poor, impatient at-bats are usually followed by words from Giambi.

It hasn't shown in the team's record, but the younger hitters Giambi mentioned have received high marks for situational hitting.

"It can be tough, mentally, when you're not winning games, because we don't want to get in the set pattern that it's easy to lose," Giambi said. "I work with them every day. 'Let's go. Put some more runs on the board. We didn't win yesterday, we're going to win today. We've got to keep that attitude.' We don't want to get away with, 'Oh, it doesn't matter,' because it does matter.

"We're not worried about our record. We're learning to play baseball. That's going to serve us well in the future."

Last year, Giambi and Helton were the ones who called team meetings when they felt selfishness was an issue. This year, the issue is a lack of pitching maturity. Although the club continues to produce better at home than on the road, there is a feeling that the approach is improving.

It's possible Giambi could end up being traded to a contending club, either before the July 31 non-waiver Trade Deadline or in a waiver deal after that point, but whether he stays or goes, manager Jim Tracy knows he has been a valuable member of his club.

"Jason has been in the middle of [improving the approach], and spearheaded some of that mentality in our clubhouse, and you can't say enough about that," Tracy said. "When you have a situation when we're 20 games under .500, you would anticipate finger pointing. We don't do things like that, and we haven't done any of that.

"We continue to come out and play hard. We know that at some point, something's going to come along that's going to be a mistake that necessitates teaching, talking, talking through it and understanding that there's a better way of doing this, and the next time it comes up, remember that."

Guthrie believes he'll turn things around at Coors

WASHINGTON -- Right-hander Jeremy Guthrie believes he is about to continue regaining his form, no matter where he pitches.

Guthrie (3-8, 6.28 ERA) gave up two runs in six mostly strong innings against the Cardinals in a 4-1 loss Wednesday night, after not having started a game since June 17, and is looking to finish the first half strong against the Nationals on Sunday.

There's still the challenge of pitching at Coors Field, where Guthrie is 1-4 with a 9.44 ERA (as opposed to 2-4 but a more respectable 3.77 on the road) and the field is playing more hitter-friendly than it has in years. The poor performance in seven games (five starts) at home led to speculation that parting would be best for him and the team. There were reportedly talks with the Blue Jays earlier this season, and predictions are the Rockies will look to move him before the July 31 non-waiver Trade Deadline. He'll be a free agent after the season.

But Guthrie, who cannot block a trade, insists he can pitch well at Coors.

"Absolutely, anybody can succeed there if they execute their pitches," said Guthrie, acquired from the Orioles in February. "There are plenty of pitchers here that are doing well. Granted, the majority of them are in the bullpen, but the process is the same -- execute, get ahead, make quality pitches and make them miss-hit or swing and miss.

"I was very excited to be traded to Colorado, to be close to home [his family lives in Utah during the offseason] and to have great fans. That's been the most positive thing, seeing how many fans we get. In Baltimore, we struggled a lot and didn't earn the support of the fans for a few years, although that's changing for them. To see fans support us even though we struggle, that's inspiring."