CHICAGO -- As Cubs pitcher Mark Leiter Jr. walked off the mound on Saturday night, the Wrigley Field faithful rose to their feet and voiced their collective appreciation for his unexpected performance. Leiter gave a quick wave in response.

"That was pretty cool, I'll be honest with you," Leiter said. "That was nice to feel that emotion."

Seven pitches into Saturday's 3-1 win over the Red Sox, the bullpen phone rang and Leiter estimated he had about 45 seconds to loosen up before jogging to the hill for warmup pitches. Starter Alec Mills had just exited, following a shot of pain in his lower back -- similar to an issue that first flared in the spring.

Leiter gave the Cubs 5 1/3 innings, allowing only one run against a talented Red Sox offense. That came after Mills first felt his back tighten up on a strikeout of Jarren Duran to open the game. Then, when Rafael Devers followed with a double, and Mills jogged to back up third base, the pitcher knew he had to leave.

What Leiter did for the Cubs was limit things to one bad moment, rather than having another game spiral out of control and forcing manager David Ross to cycle through a conga line of relievers.

"I'd much rather talk about that," said Mills, who missed the season's first three months due to lower back and right quad injuries. "What he did was special."

Really, this has been the story of the Cubs' rotation this season. The front office made starting pitching its top offseason priority -- signing veterans Marcus Stroman, Wade Miley and Drew Smyly to join the Kyle Hendricks-led group -- and continuous health issues have held the group back.

"I truly think that [if] everybody stayed healthy and guys performed," Stroman said, "we could've been right there, too."

Let's walk through where some things stand with the rotation:

• Stroman, who was the Cubs' big free-agent signing via a three-year deal worth $71 million, has been on the 15-day injured list since June 7 due to a right shoulder injury. He is slated to make a Minor League rehab start with Triple-A Iowa before potentially being activated.

"After this, I should be good to go," Stroman said. "I would assume that I would be in there every fifth day and feel good the rest of the year."

• Smyly tossed three no-hit innings on May 30 against the Brewers and then exited with a right oblique strain. He has built up to a point where his first Minor League rehab outing is planned for Monday with either Iowa or High-A South Bend. Ross laughed when asked if he had a preference for which affiliate.

"I don't care if it's a live BP here," Ross said. "Just throw and come back healthy and get to feeling where you can compete at this level."

• Miley has been plagued by left arm issues since the spring, logging four starts with the Cubs around stints on the IL. The veteran lefty is currently building up in the early phases of a throwing program.

The absence of those three veterans -- plus the loss of Adbert Alzolay to a right shoulder strain during Spring Training -- has created a situation in which the Cubs have used the most starting pitchers (13) in the National League to date this year. The team used 12 all of last season.

There have been MLB debuts (Caleb Kilian and Matt Swarmer), bullpen games (started by Scott Effross and Daniel Norris) and arms trying to prove they deserve to stick around (Adrian Sampson and Leiter).

More significantly, Justin Steele and Keegan Thompson have started to establish themselves as reliable starters who can work deep into games. Steele has turned in a 3.38 ERA in his last six turns, while Thompson has logged a 2.45 ERA in his past three (at least six innings in each start).

"They're amazing, man," Stroman said. "I think those guys are really legit. They're learning. They've both been dealing. But I think those guys are going to be kind of, hopefully, household names in the next few years as they progress."

In the meantime, outings like the one Leiter provided are helping the Cubs hold things together as the sidelined starters move closer to returning to the fold.

"I was really impressed," Ross said. "The circumstances made it even better. That was a really good performance -- a big-time performance."

One deserving of an ovation.

"It was definitely a cool moment to walk off the field to that," Leiter said.