CHICAGO – When Justin Steele dropped to the grass in Globe Life Field on Opening Day, grabbing at his left leg, it was easy to think through worst-case scenarios for the Cubs’ rotation. A little more than a month later, the lefty rejoined a group that has more than held together in his absence.

Chicago’s starting staff carried on as one of the top rotations in baseball while Steele -- a Cy Young Award contender last year -- was on the injured list with a hamstring strain. On Monday night, the Cubs were dealt a 6-3 loss, but the sound of Johnny Cash’s “God’s Gonna Cut You Down” as Steele warmed up was greatly welcomed by the Wrigley Field faithful.

“We're all really excited,” fellow Cubs starter Jameson Taillon said. “Anytime you add someone like Steeley back, that's just huge, no matter who he's replacing or what's going on. You add someone like that, that's a big deal.”

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Steele did not miss a beat, giving the North Siders 4 2/3 shutout innings in his first outing since his abbreviated start on March 28 against the Rangers. That extended the active scoreless streak by Chicago’s rotation to 23 innings. Hayden Wesneski, Taillon and Javier Assad each blanked the Brewers in the previous three-game series.

Entering Monday’s game, the rotation spun a 2.61 ERA over the previous 21 games dating back to April 14. Only the Phillies (2.53 ERA) had a lower mark in that time frame in the National League. Overall this year, lefty Shota Imanaga (5-0 with a 0.78 ERA in six starts), Assad (3-0 with a 1.66 ERA in seven starts) and Taillon (3-0 with a 1.13 ERA in four starts) have led the charge.

In the time period that Steele was on the shelf, the Phillies (2.65 ERA) and Dodgers (3.11 ERA) were the only NL clubs with a better showing than the Cubs (3.16 ERA) from their respective rotations.

“It’s kind of hard to put it into words,” Steele said of the collective performance of Chicago’s starters. “I feel like everybody in the rotation that was pitching while I was gone is like Top 10 in MLB right now, as far as ERAs go. The rotation’s been almost flawless as of late, so you just kind of have to tip your hat. It’s a testament to the depth we have.”

Losing Steele in the season opener was not the only obstacle for the Cubs’ rotation.

Jordan Wicks won an Opening Day job, but landed on the injured list after five starts due to a left forearm strain. Veteran righty Kyle Hendricks logged a 12.00 ERA through five starts before heading to the IL with a low back strain. Taillon opened the year on the IL due to a back problem that flared in Spring Training.

The early setback with Taillon paved the way for Assad to win a rotation job to start the season. The subsequent issues led to Ben Brown and Wesneski getting opportunities to start. So far, Brown has logged a 2.84 ERA through four turns in the rotation, while Wesneski has been stellar (0.87 ERA) as well in his two spot starts.

“[It’s been] as good as you can hope,” Cubs president of baseball operations Jed Hoyer said. “All those guys have stepped up and really produced for us, and that's what you need to get through injuries. And there's going to be more. There's going to be more things that happen. And we just have to be able to withstand those things.”

The only hurdle left for Steele to clear in his comeback is building his volume back up.

In his return against the Padres, Steele was on a pitch count after pitching in just two rehab outings (one in extended Spring Training and another with Triple-A Iowa). He bowed out in the fifth inning after 68 pitches on the night. The Padres then pounced on Chicago’s beleaguered bullpen with a six-run outburst in the sixth.

“Justin pitched very well,” Cubs manager Craig Counsell said. “We've got to build up some endurance still, but for where we're at, I thought he delivered a great performance. Exactly what we needed and a great first step.”

And getting Steele back is a great step to lengthening out an already deep rotation.

“We've got six, seven really legit options, which is super exciting,” Taillon said. “If you come in to play us for a series, it's not like you can circle a guy and be like, 'Man, I hope we get him, or miss him.' Hopefully, you come in and it's like, ‘Man, we've got three tough guys every series.'”