Ever since the Cubs left Chicago to head to the West Coast last week, it feels like their starting rotation has figured something out.

Starting with Kyle Hendricks’ 8 2/3 inning gem on May 9 to open the series in San Diego, the Cubs’ rotation has turned a corner in terms of being the productive group that the team needs to find any sort of success this season.

Over a nine-game stretch from that day through Wednesday, Cubs starters owned a combined 2.54 ERA (second-best in the majors), a .227 opponents’ average and a 1.13 WHIP (both tied for 10th in the majors) and a 1.4 fWAR (No. 2 among all 30 big league clubs). The Statcast numbers played, too. The Cubs had the second-best big league mark in barrel rate (2.8%), and their hard hit rate (35.4%) was the ninth-lowest.

And on Thursday night, when the Cubs welcomed the Diamondbacks to Wrigley Field, that rotation reached full strength with Marcus Stroman’s return from the injured list.

No, “The Stro Show” wasn’t exactly dominant in its entirety.

In five innings, he gave up two earned runs and five hits. He did, though, pitch three perfect innings to begin the game, and before he left after the top of the fifth, he’d struck out six batters, had recorded 11 whiffs on 39 swings and had seen a slight increase on the velocity on the sinker (by far his most used fastball).

But for three innings — three perfect innings, at that — Stroman looked exactly like he did prior to his 11-day COVID-related IL stint.

He needed just 20 pitches to breeze through the first two innings, punching out two and picking up three ground outs and a fly out. The third was easily his best frame of the day, as he struck out all three hitters he faced on only 13 pitches.

The fourth inning was where he struggled, as he gave up a lead off homer followed by two more runs on three base hits. But he was then able to go back out for the fifth and finish out his night with a scoreless frame.

“Definitely a priority on just keeping my mechanics as simple as possible today,” Stroman said. “I thought I competed pretty well and I was in the zone. I’ve had layoffs like that before in the past and I’ve been kind of all over the place, and just to be around the zone and give my team a chance, I think it’s something good to build off of.”

Before being put on the shelf, Stroman hadn’t pitched since May 1 in Milwaukee. There, he turned in the finest performance by a Cubs starter to that point in the season, lasting seven shutout innings, striking out five and allowing just two hits. That followed a six-inning quality start in Atlanta five days earlier, which made it feel like Stroman was finally finding his form.

With Stroman now back in the fold, that gives the Cubs the five-man starting group they envisioned leading the charge after they brought it together during the spring. Just take a look at the five starters that were on schedule prior to Wednesday’s 3-2 loss to the Pirates:

• Drew Smyly vs. Pittsburgh on Wednesday
• Stroman vs. Arizona on Thursday
• Kyle Hendricks vs. Arizona on Friday
• Justin Steele vs. Arizona on Saturday
• Wade Miley vs. Arizona on Sunday

That’s a starting five the Cubs are comfortable rolling out there one game at a time, and it’s the starting five they hoped they would’ve been rotating much sooner than the seventh week of the season. And if you need some verification on that, just ask the person who assembled that group.

“It’s hard to get on a roll when you don’t have consistency in your rotation,” president of baseball operations Jed Hoyer said. “We’ve had a hard time doing that with injuries and things so far. So let’s hope this is the beginning of having some turns through the rotation and we can have some consistency.”

Stroman’s IL placement 11 days ago almost necessitated that Miley be activated from the IL, which he’d been on since the season started. Now that both have returned to the team, there’s optimism that the rotation’s recent performances will become more commonplace more stability in the group.

“I think you just build off of each other,” Hendricks said Wednesday. “It’s kind of that internal, friendly competition in a way, but you just want to push each other to do better. You see the other guys doing well, it kind of picks up your game, and you just learn. You learn from watching guys go out there and have success, how they’re doing it and how they’re going about it. I think just having everybody in this rotation coming back together — Stro coming back, now Wade back — it’s just going to hopefully create that consistency that we’re looking for.”

Now, consider what the rotation has done over the previous 10 games.

In that time, starters have put together three quality starts after having just three through the first 27 games. Those included:

• Hendricks’ aforementioned gem
• Steele’s career-high 10 strikeout performance on Sunday
• Miley’s seven shutout innings on Monday

Meanwhile, the seven starts that weren’t “quality” included:

• Stroman’s return from a long layoff on Thursday and Miley’s return from an even longer layoff on May 10
• Hendricks’ 5 2/3 innings of one-run ball on Saturday
• Smyly’s 4 1/3 innings of three-run ball on Wednesday and six innings of four-run ball on Friday
• Two starts from multi-inning bullpen weapon Keegan Thompson (the second of which saw him throw five shutout innings)

Really, if those are the “bad” outings from your starters, things could be going worse. They weren’t all gems, no, but they at least give off the impression that the Cubs’ rotation is starting to find its form. And that’s certainly a welcome sign for the entire team.

“I think we’re going go as far as our starting rotation goes,” Yan Gomes said. “I think that’s said with every team. I feel like now, you don’t want to give the excuse of the shortened spring training or anything, but you’re starting to see a lot of guys get in their rhythm and not fall apart as quickly as maybe we were. We’re just trying to figure things out. You’re starting to see guys get in their rhythms quicker during the games, and now we’re able to really go all out with our reports.”

Earlier in the week, manager David Ross was asked if what the starters have done over the past week-plus was sustainable.

Sure, they’d been performing better, but at least part of the recent success came in a softer part of the schedule following the 13-game gauntlet against the Braves, the Brewers, the White Sox and the Dodgers. Plus, 10 games is a very small sample size. Can these guys do it over the rest of the season?

“I definitely think that’s sustainable,” Ross said. “I think we’ve got a really good pitching staff as a whole. I don’t think we’re this dominant staff that everybody is going to look at, but the guys know how to pitch and how to compete. I think they’re going to give us a chance to win more nights than not.”

If this past 10-game stretch is any indication, it looks like they’re starting to get there.