ATLANTA -- A chance for the Cardinals to sustain a run of quality starts through a full turn of their rotation came to an undramatic end on Wednesday night with another mostly nondescript start from right-hander Michael Wacha.

And that’s been the issue.

While Wacha did keep the Cardinals close in what would finish as a 4-0 loss to the Braves at SunTrust Park, he still hasn’t regained the form that had him headed toward an All-Star invitation before an oblique injury ended his season last June. That’s led to a maddening run of mediocrity. "A grind," Wacha called it.

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“The past few starts, for sure,” he said.

Wacha has yet to record an out in the seventh inning this season and has finished six frames just twice in eight starts. On Wednesday, a pitch count of 90 ended his night after five innings. His fastball command came and went, as did his biggest mistake of the night, an up-and-over-the-plate fastball to highly touted prospect Austin Riley, who crushed it for a homer in his Major League debut.

“Very few times did I hit the spot when I was going to that certain spot,” said Wacha, who also walked four and allowed an unearned run on an errant throw. “I just have to keep working at that and get it to where I need it to be.”

The most uncharacteristic thing about Wacha’s night was that the Cardinals’ offense couldn’t bail him out. After the team averaged 9.49 runs of support through his first seven starts, the right-hander got none as the offense stalled against right-hander Mike Soroka. It marked the third time the Cards have been shut out this month.

“We ultimately have to figure out a way to get that hit,” manager Mike Shildt said, one day after his team had clubbed 14 of them.

Yet for Wacha, that excess of run support has only masked the troubles that have trailed him since he opened the year with consecutive one-run starts. Since then, he has posted a 6.23 ERA over six games while averaging 18 pitches per inning. With four more walks issued on Wednesday, he has given up 14 free passes during that stretch. Opponents have tagged him for seven home runs.

So what’s the culprit? Location for one, as was reinforced when Riley obliterated a fastball for his first MLB hit. To maximize his secondary pitches, particularly his can-be-devastating changeup, Wacha must establish command of his fastball. That’s been a recurring trouble spot since he returned from a knee injury that briefly sidelined him in April.

“It kind of seems like it comes and goes every now and then,” Wacha said. “It gets me behind in counts, and then I have to fight to get back in it. That creates long at-bats, long innings and gets that pitch count up pretty quick.”

And then there’s the radar readings. All four of Wacha’s pitches have dropped in velocity this season, including the four-seam fastball, which, as it has all year, averaged 92.5 mph on Wednesday. That’s down from 93.6 mph in 2018 and 95.1 mph in 2017. Of the 37 four-seam fastballs Wacha threw on Wednesday, not one hit 95 mph on the radar gun.

The home run Riley hit came on a fastball clocked at 89.9 mph.

“It might be the fact that it doesn’t look like he’s completely synched up with his mechanics,” Shildt said when asked about the velocity dip. “A lot of times, if you’re synched up with your swing and mechanics, then everything is working together and you maximize your body and everything comes out a little cleaner. So he may be fighting himself a little bit.

The average velocities of Wacha’s cutter (88.7 mph) and changeup (85 mph) are also lower than they’ve been in any of his previous six seasons.

“I mean, I don’t really know,” Wacha answered, when asked if he might know why. “I’m just trying to give it my all and trying to make pitches. It’s down a little bit right now. We’ve had some cold games, cold weather stuff. Hopefully, it starts getting back up there a little bit.”

What it’s not, he confirmed, is a physical issue. Wacha insisted that his arm and body feel fine.

“We know that when it clicks, how dominant it can be,” Shildt added. “We’ve seen that for years. [His side sessions] have been good. Reports have been positive. When it clicks, we’ll be really happy.”