MILWAUKEE — Before Sunday’s series finale at American Family Field, David Ross talked about the improvement he hopes to see from his Cubs team in May.

The first thing he mentioned was the rotation.

“Good starting pitching is gonna need to happen,” Ross said. “Everything goes with how those guys set the tone on the mound.”

Marcus Stroman did exactly that in a 2-0 Cubs victory Sunday — on his 31st birthday, no less.

Stroman completely neutralized a Brewers team that put up 20 runs in the first 2 games of the series. The Cubs right-hander allowed only 3 baserunners in 7 shutout innings — and erased 2 of those with a pair of double play grounders in the first 2 innings.

Patrick Wisdom’s homer and Seiya Suzuki’s RBI double provided the offense and gave Stroman his first win in a Cubs uniform.

“Stro just took the bull by the horn, so to speak, and took us all the way to the 8th,” Ross said. “Really nice job all the way around.”

Stroman lowered his season ERA to 5.13 and has now turned in back-to-back quality starts after a couple of bumpy outings to begin the campaign.

“He’s been working his absolute tail off during starts,” catcher Yan Gomes said. “It’s starting to finally come around. I think he’s starting to come together and we’re starting to see who that Stroman is — the guy full of confidence on the mound. That outing showed it.”

Stroman signed a 3-year, $71 million contract with the Cubs in December and sometimes that type of deal can put undue pressure on players to perform right out of the gate.

“What I’ve experienced from former teammates and just my short time managing — guys that come to new environments with big contracts, you put a lot of pressure on yourself early on,” Ross said. “You try a little bit harder. You want things to work out. Jon [Lester] did that in his first year here.

“You want these guys to settle in. It’ll happen. Continue to work, find their rhythm, find themselves. It’s a really confident young man and believes in himself and wants to do well for the group.”

Between the new contract, the lockout and the subsequent shortened Spring Training, it certainly hasn’t been a smooth first few months for Stroman in Chicago. But he refused to use any of that as an excuse.

“I gotta pitch better,” he said, simply. “I want that to be the standard. That’s how I feel good. I’m the toughest critic on myself. Tomorrow, Tuesday, I’ll be working on however I can be better for next start against the Dodgers.”

With the win Sunday, it marked the second time this season the Cubs were able to pull out a victory facing the reigning NL Cy Young winner (Corbin Burnes).

Burnes did not get the loss on Opening Day, but the Cubs touched him up for 3 runs in 5 innings. On Sunday, the offense did enough to chase Burnes from the game and avoid the sweep.

“That guy’s incredible,” Stroman said of Burnes. “One of the very few pitchers I watch video on and really dive into his stuff — his sequencing, his tunneling. He’s incredible with his pitch mix. Anytime you go up against that guy, you know you have to bring your A game.”

David Robertson came out of the bullpen for a 4-out save (his 5th of the season) to preserve the victory. The veteran still has not allowed a run this season in 9 appearances.

The Cubs head home for an off-day Monday before the Wintrust Crosstown Series kicks off Tuesday night at Wrigley Field.

“Every win’s a big win for us,” Robertson said. “Obviously we haven’t had the best road trip but it’s nice to pick up a win, especially on getaway day going into an off-day.”

Gomes agreed.

“I wish we could’ve had better games the other 2 games,” Gomes said. “It’s definitely going to be a confidence booster taking the No. 1 and taking a win from them today.”