"The home runs bug me a little bit because I feel like, with the sink that I have, that I should be able to keep the ball in the yard," said Westbrook. "Tonight, that wasn't the case."
All four of the earned runs the Braves scored against Westbrook came via two home runs. Westbrook had served up only three in his first 56 innings this season.
While Matheny said he felt Westbrook's outing "was a lot better than what [the line score] showed," there were still elevated sinkers and command issues, both parts of those trends that have emerged this month.
"Every time he's down, he's nasty because the ball is moving a lot," said catcher Yadier Molina, who contributed a four-hit night. "For him, the key is keeping the ball down. And the ball is up."
Westbrook's sixth pitch of the night was up too much to Michael Bourn, who drove it over the wall to give the Braves an early advantage. In the third, a three-run homer from cleanup hitter Dan Uggla pushed that lead to four.
"The three-run homer wasn't a super-mistake pitch," Westbrook said. "But it was just too good of a pitch."
Preceding it were a one-out walk and infield single. The home run was Uggla's third in his last seven games.
"I was just happy to get a pitch I could handle," said Uggla, "and I put a good swing on it."
Atlanta scored once more off Westbrook in the fifth, despite recording only one hit -- a single -- in the inning. A walk, throwing error by Westbrook and wild pitch led to the unearned run. Expecting Westbrook's split-changeup to finish down and away from the batter, Molina couldn't react when Westbrook yanked it to the inside part of the plate.
It went to the backstop, allowing Jose Constanza to score easily. That play put the Braves ahead, 5-2, at the time and loomed largely in the outcome.
"All that added up," Matheny noted. "It ended up being a very important run."
Westbook's outing ended with that inning, too, as Matheny opted to send a pinch-hitter up in Westbrook's place when the Cardinals put two runners aboard in the following frame.
Though he allowed only five hits on Tuesday, Westbrook has now gone five or fewer innings in three of his last five starts. He pitched no fewer than 6 1/3 in his first six outings. His numbers tell the reason why.
The right-hander could have hardly started the year much better, running out to a 4-2 record and allowing 34 hits, 10 walks and eight earned runs in 41 innings.
But beginning with a May 14 outing against Chicago, the results have taken a not-so-encouraging dip. His last four outings have spanned just 20 innings, and Westbrook has given up 19 runs (17 earned) on 13 hits. He has walked nine, including three on Tuesday.
And the common thread through these so-so starts seems to be the sinker.
"It gets back into the whole inconsistency of it," Westbrook said. "I need to get back to where I was in spring and in April, being more consistent down in the zone. I just need to do a better job. That's all it boils down to. I haven't been very good these last four starts."
Beginning with a two-run fourth, the Cardinals chipped away at the deficit. Molina drove home three with his third four-hit night of the season. A fourth-inning single plated St. Louis' first fourth-inning run. Molina's eighth home run of the season gave the Cards a sixth-inning tally against Atlanta starter Randall Delgado, the game's eventual winner.
Trailing by two runs in the seventh, the Cardinals utilized three two-out singles -- the final one by Molina -- to inch one run closer. Matt Adams couldn't push St. Louis further, however. With runners on the corners, Adams went down swinging against reliever Jonny Venters.
The Cardinals, who lost despite doubling the Braves' hit total, ended up stranding eight runners on the night. The team went 2-for-8 with runners in scoring position, with both of those hits coming off Molina's bat.
"I'd rather have my 1-for-5 [Monday] night and the win and not to take the 4-for-4 and the loss," Molina said afterward. "But I feel pretty good at the plate."
With the loss, the Cardinals are assured of finishing with a losing May record. That record sits at 13-15.
They also continue to fare poorly in one-run games, which explains how the Cards easily lead the National League in run differential (plus-68), and yet are only four games above .500.
"I know that those games make you better in the long run," Matheny said. "The best teams I've been on are the teams that played in a lot of tight games. Once they get used to the pressure, they thrive on it. But we do need more of them to go our way. For us to keep putting the pressure on like that, it's going to pay off."