DENVER -- At Coors Field, where the air is thin and the ball loves to fly, assembling a reliable stable of starting pitchers is a special kind of challenge.
But August has been kind to the Rockies' starters, who are on pace for their best month of the year. Although Colorado is a modest 6-7 in 13 games this month, the starting staff has posted a 4.08 ERA, an improvement from the 4.24 ERA it carried in April -- the rotation's best stretch to this point.
The timing is surprising, since the Rockies have done it without Tyler Chatwood, who had become a cornerstone of the rotation and boasted the staff's lowest ERA (3.15) before right elbow inflammation sidelined him at the end of July.
And Chatwood's absence has placed an even heavier burden on the rotation's two other pillars -- Jhoulys Chacin and Jorge De La Rosa.
Chacin has led the charge, chewing through innings like a true ace and shining with a 1.57 ERA in three starts this month. The right-hander hasn't necessarily overpowered hitters, and he said after a superb eight-inning, one-run start Monday that a sinking fastball was a critical factor in his recent dominance.
"I think his fastball command's always a key," pitching coach Jim Wright said. "It is for all of them, but especially for [Chacin], because he's got such a good sink on his fastball that to be able to command it, [you need to] have the confidence to know you can throw and throw it where you want, keep the ball on the ground."
Though not quite as dominant in August, the left-handed De La Rosa has been steady with a 3.38 ERA over 16 innings.
Rockies manager Walt Weiss attributes much of the growth for Chacin and Chatwood to big league experience. It's easy to forget that Chacin, in his fifth season in the Majors, is just 25, and De La Rosa made only three starts last year as he recovered from Tommy John surgery in 2011.
"I think it had a lot to do with experience," Weiss said. "Not in Jorge's case, because he's been around. But the other two guys [Chacin and Chatwood] I think are maturing as we speak. Jorge is a case of getting back to form after missing a lot of time."
Wright said Chacin, De La Rosa and Chatwood each made minor mechanical adjustments this year, but Wright also sees the confidence and comfort of pitching at baseball's most elite level as equally important to their success.
Of the three other pitchers who have earned a start in August -- Juan Nicasio, Chad Bettis and Jeff Manship -- none have completed a full season in the Majors.
"Especially at this level, at times guys are here because their stuff is ready, but maybe emotionally and command-wise they're not quite there," Wright said. "So their learning curve may get finished up here or their final stage of development is at this level, which is a little tougher to polish yourself off."
Nicasio, 24, takes the mound Friday against the Orioles. He has been inconsistent since returning from a brief stay with Triple-A Colorado Springs in mid-July. After looking utterly dominant in a pair of scoreless seven-inning outings in his first three starts back with the Rockies, Nicasio has gone 0-1 with a 6.30 ERA in August.
Bettis, the club's second-round pick in the 2010 First-Year Player Draft, has made progress in each start since his Aug. 1 big league debut. To borrow Wright's words, Bettis is a "bulldog," who doesn't shy away from attacking hitters with his fastball. That fastball will only be more valuable once Bettis gains a better grasp of when to mix in a changeup that he's been experimenting with since college.
"It's all a learning process," Bettis said. "I'm still new up here, so I'm trying to figure out different teams and their strategies and stuff like that. I feel like I'm learning, though, pretty fast."
Manship, who spent parts of four seasons with the Twins, took a step back from an effective start against the Mets in Tuesday's loss to the Padres, when he surrendered six runs in five innings.
The younger pitchers have also been more than happy to hear the advice of their more proven counterparts. They share the insider knowledge about particular teams and batters that Bettis said he's still picking up.
"Sometimes [Bettis asks me], 'How did you pitch this guy?' or something like that," Nicasio said. "Chacin, De La Rosa … can help me and I can help some guy when he [asks me], 'Nicasio, how are you pitching this guy?' I tell him I throw in or away."
With Drew Pomeranz on the disabled list, it's turned into a two-man race between Bettis and Manship auditioning for that fifth spot in the rotation once Chatwood returns. Bettis said he tries to avoid the thought of any such a competition, preferring to focus on each start and avoid stressing over a decision he doesn't have the power to make.
That Colorado has still assembled one of its stronger stretches of the year despite such movement at the back end of the rotation is largely a tribute to Chacin and De La Rosa.
Like many others around the Majors, Wright is searching for someone who will make that critical lunge forward and solidify their place on a big league staff.
"That's what you hope for, someone to take advantage of the opportunity and make it their job," Wright said.
Ian McCue is an associate reporter for MLB.com