ST. LOUIS -- When hitters are standing there, bickering with the home-plate umpire or frozen in disbelief, it usually means Michael Wacha is having a good day.

That’s because Wacha is 6-foot-6 and, when he is most effective, is typically obliterating the lower half of the strike zone. The ball bores through the hitting area at a downward angle, meaning it doesn’t stay there long, is hard to square up and usually looks low by the time the catcher has it. It's like trying to hit an acorn blown out of a tree.

The St. Louis Cardinals first noticed this phenomenon in spring training several years ago. Wacha’s own teammates were complaining that his pitches were low while taking live batting practice off him.

Michael Wacha's six scoreless innings Monday were a welcome sight for the Cardinals. Jeff Roberson/AP

Six Milwaukee Brewers stood there in apparent disbelief as plate umpire Bill Welke called them out on strikes Monday afternoon during a 10-1 Cardinals win in their home opener. By the time Wacha took the mound in the fourth inning, his job had been simplified by St. Louis' barrage of extra-base hits and runs.

“You go out and try to get back to the dugout as quick as possible so we can score a lot of runs,” Wacha said.

But his six scoreless innings might have been the most important development in a day of feel-good story lines for the Cardinals in their home opener. Hall of Fame players showed up in red sport coats to the delight of a sellout crowd. The Clydesdales chugged around the warning track. Young hitters kept funneling electricity to the rest of the lineup, and some slumping players jolted to life.

But the team’s hitting funk stopped pretty much the minute they left Pittsburgh, with its chilly temperatures and stingy Pirates pitching. Until Monday, the Cardinals had been waiting for their starting rotation, with its sky-high expectations and 6.25 ERA through the first week, to get hot.

With Wacha darting 93-mph fastballs and cartoon changeups at the Brewers for six scoreless innings, his performance became a big talking point for manager Mike Matheny afterward. Matheny said catcher Yadier Molina and pitching coach Derek Lilliquist huddled with Wacha after he gave up a couple of hard-hit singles in the first inning to remind him to get on top of the ball and drive it down. Molina set up low targets, Wacha started hitting them and the Brewers had a miserable afternoon in the shadows. Only one Brewer who struck out against Wacha, Domingo Santana, went down swinging.

“Michael hit his stride and, hopefully, that’s something we can watch him replicate here for a while,” Matheny said. “That was as good as we’ve seen him for a while.”

With Adam Wainwright still searching for clean mechanics after a year off from pitching while he recovered from leg surgery, the continued development of Wacha and Carlos Martinez is key to the Cardinals’ chances. Both pitchers showed signs of wearing down near the end of last season, so to see them fresh and effective again is a big boost to the team’s psyche. Martinez and Wacha have the best raw stuff in the Cardinals’ rotation, and both have ace-caliber upsides.

Wacha (1-0) was mildly frustrated after his 4 1/3-inning start in the second game of the season at Pittsburgh. He gave up 10 hits and had just three strikeouts. He made a point of limiting his mistakes and found that, by keeping his fastball low, his changeup and curveball became more effective.

“I feel like it really opened up from there,” Wacha said.

The Cardinals have scored 34 runs in their past three games, though the fact they were playing the Atlanta Braves and Brewers might have had something to do with that. Both teams finished in the bottom five in the National League in ERA last season and haven’t exactly offered convincing evidence they’ve turned things around for 2016.

The Cardinals might be delighting their fans with extra-base hits -- eight doubles and two triples on Monday alone -- but they’re still all about pitching. They’ll be looking for a positive stride from Mike Leake on Wednesday and then more of the same from Jaime Garcia and Martinez later in the week.

Wacha built a solid foundation on a cool Monday afternoon by building from the bottom up.