DENVER -- As the Chicago Cubs put Sunday's grueling 18-inning loss and a New York Yankees series sweep behind them and head to the thin air of Denver, everyone in the clubhouse agrees: The past week was a taxing one for the bullpen, and a few more innings from a veteran starting staff could help matters.

At least two Cubs starters say they're ready to do exactly that, though their manager says they have to earn it first.

“We definitely have used the bullpen quite a bit lately, but there’s various reasons for that,” John Lackey said Sunday. “It’s not all on us.”

Lackey didn’t elaborate who it’s on, but he might have simply been referencing back-to-back starts by Brett Anderson that totaled just 1 2/3 innings. Granted, the other four starters are not responsible for that, but it’s not as though they’ve been lights out, either. Or perhaps Lackey is trying to tell his manager he’s ready for more. Kyle Hendricks sounded the same horn.

“There have been a lot of games where we could have gone deeper in games,” Hendricks said. “Pitch-count-wise, we were at 90 or even less than that. A lot of us. We’re getting into the sixth with decent pitch counts. If we go 100, 110, we’ll get six or seven innings.”

Hendricks’ manager didn’t exactly agree with those sentiments, as pitch count isn’t usually a determining factor when he's deciding whether to pull a starter. Effectiveness is, however. And observers would be hard-pressed to say the Cubs starting staff -- even minus Anderson – has been all that effective.

“I think they’ve been given all the opportunity to pitch as long as they should be pitching in these games to this point,” Maddon said. “As we pitch better, they’ll pitch longer into the game. It’s pretty simple stuff.”

According to ESPN Stats & Information, the top four Cubs starters -- Jon Lester, Jake Arrieta, Lackey and Hendricks -- all average just less than six innings per start. It’s their pitches per start, based on those innings, that is interesting: Lester averages the most, 104.3; Lackey is at 99.2 pitches, followed by Arrieta at 95 and Hendricks at 93.5. That’s a lot of pitches without completing six innings. And it’s not as if they’re passing the eye test, so Maddon might not be wrong in saying they have to earn it. Even Hendricks understands the need for more efficiency.

“We need to start taking more of the workload and getting deeper into games,” Hendricks said. “That starts with getting quicker outs, pounding the zone earlier.”

Maddon has often had to push back against his veteran staff, as pulling guys such as Lackey, Lester and Arrieta can require some explaining. Sometimes, he simply needs to pinch hit for them when the Cubs are trailing early in games (as has happened often this year), while other times the manager is reluctant to send his starter out for another inning in fear of a high pitch count forcing a mid-inning change with men on base.

“I don’t want our guys coming into a bad inning,” Maddon said.

If last week wasn’t rough enough -- the Cubs employed nine relievers in the bullpen on Saturday and then seven in Sunday's epic slog -- it only gets tougher for the starting staff over the next three days. They’ll spend it at Coors Field against a high-powered Colorado Rockies team that ranks third in the NL in runs scored at home and is capable of putting up a big number at any time. The Cubs' 11.32 first-inning ERA will be put to the test.

“Colorado is a tough place to pitch,” Lackey said. “It’s not ideal, but the other guy has to pitch there, too.”

Hendricks added: “It’s definitely a little like Arizona. The ball doesn’t spin as much. Almost back off a little and be under control.

"Keep the ball down. It’s not spinning as much, so you can’t get frustrated with it. You need to learn how to back off.”

It would probably take a leap of faith from Cubs fans right now to believe the team will get three straight quality starts at Coors Field, whereas last year, a non-quality start at any point during the season was actually newsworthy.

“We realize it,” Hendricks said. “We talk about it amongst us. Like I said, we have to pick it up a little bit, we haven’t gotten deep into games. There’s a lot more innings left out there. We talk about that, too. There are both sides to it.”

Maddon might now be inclined toward using his rotation more no matter the pitch count -- Lester threw 120 pitches in Sunday night's loss to the Yankees -- while looking to rest a depleted bullpen.

“Now, if you have a less rested bullpen, then you’re going to attempt to have your starter pitch more deeply into the game,” he said. “If you have a more rested bullpen, then of course you’re going to utilize your guys. Quite frankly, to this point, I think the numbers are right on.”

He means, until Sunday, his starters have pitched exactly as much as they’ve deserved -- no matter what they say.

“I don’t work off a number,” Maddon continued. “I work off effectiveness. I’m looking at your next start. I’m looking at your body of work. I am looking at where you’ve come from.

“There’s a variety of things I look at. It’s not just a number. It’s not a 100-pitch exercise.”

The historically good staff from a year ago can take matters into its own hands, starting with its biggest challenge yet: Nolan Arenado, the Rockies and Coors Field. That’s not to say the Cubs are in any kind of panic mode. Early to mid-May usually doesn’t elicit it, though improvement would be nice.

“We have a long way to go,” Lackey said. “We have five months to go. We’ll be just fine in the end.”