CINCINNATI -- If it wasn't official before, it is now. Lance Lynn is in a slump.
The right-hander, who lost his last four decisions entering Thursday's start against the Reds, tied his single-game high by allowing three home runs en route to the first loss of his career to the Reds, 6-2, at Great American Ball Park.
"It's definitely not fun, especially with the stuff I've had lately," said Lynn, who's allowed at least four earned runs in each of his last five starts. "I think it's some of the best I've had all year. It's frustrating."
Manager Mike Matheny couldn't disagree.
"It's more frustrating for him," Matheny said. "You watch his stuff and how it moves and you scratch your head, because you know how good he can be."
Especially against Cincinnati. Going into his 29th start of the season -- another career high -- Lynn (13-10) was 3-0 with a 3.55 ERA in five starts and three relief appearances against the Reds. He logged all three decisions and a 2.67 ERA in four starts this season, but the Reds reached him for seven hits and four runs with four walks and six strikeouts while making him throw 102 pitches over five innings.
"If you look at the game overall, I made three bad pitches that they hit for three home runs," he said. "That usually doesn't happen. You take away those three pitches, and it's a totally different ballgame."
The Cardinals tied a season high in allowing four home runs while slipping 1 1/2 games behind National League Central-leading Pittsburgh and seeing their lead over third-place Cincinnati shrink to 1 1/2 games. St. Louis is scheduled to open a nine-game homestand on Friday with the first of three games against Pittsburgh.
St. Louis, which finished a seven-game road trip through Pittsburgh and Cincinnati with a 2-5 record, had won the last seven series against the Reds, including three in Cincinnati, before losing three out of four in the final series of the season between the two teams.
"Boy, that was a big series right there," Reds manager Dusty Baker said. "You try not to think about games in the past, but that game last night [a 5-4 St. Louis win in 16 innings] still hurts, but that's OK. A good team, that's what they do. They bounce back. You have to be a resilient team."
Lynn got the first two batters out in the first inning but walked the bases loaded before coming back to strike out Todd Frazier to end the threat.
Lynn retired the first two batters in the second inning before Reds left-hander Tony Cingrani, activated from the 15-day disabled list before the game, almost singlehandedly manufactured a rally that left Cincinnati leading, 1-0. Cingrani, who'd been sidelined with a strained lower back, beat out a bunt, stole second, went to third on a wild pitch to Shin-Soo Choo and scored on Brandon Phillips' sharp grounder to shortstop Ryan Jackson. Jackson backhanded the ball, but second baseman Matt Carpenter dropped Jackson's throw. The play was ruled an infield hit.
"It was kind of baffling," Matheny said. "You would see [Lynn] make really good pitches and work ahead in the count and get quick outs, and the next thing you know, they're hitting the ball hard. You see him make terrific pitches and get two outs, and the next thing you know, he's catching too much of the plate and they're not missing."
Cingrani figured he had nothing to lose with his bunt.
"It was 0-2," Cingrani said. "I figured if I got thrown out, Choo leads off the inning. They don't really pay too much attention to me over there, so I figured it was a good play."
The Reds added solo home runs by Frazier in the third, Choo in the fourth and Jay Bruce in the fifth, answered only by David Freese's 428-foot solo shot to center field on Cingrani's first pitch of the fifth. It was Freese's seventh homer of the season and first since Aug. 4 in Cincinnati.
The Cardinals added a run in the sixth after Carpenter hit a one-out triple to deep right-center and scored on Cingrani's wild pitch. Shane Robinson followed with a single and Matt Holliday walked on four pitches, but reliever Zach Duke got Carlos Beltran to bounce into a threat-ending double play.
Bruce added an RBI single in the sixth, and Frazier launched his second homer of the game in the seventh off Seth Maness.
Mark Schmetzer is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.