The Reds' four-game winning streak is done, and now that the club is at 70-82 for the season, this loss officially guaranteed Cincinnati its eighth straight losing season.
For the second straight time, command was an issue as Volquez tied a career high with six walks while giving up four earned runs and three hits over seven innings. He did, however, strike out five.
Like his previous outing in Arizona, Volquez couldn't be sure where the ball would go once it left his hand.
"Tonight, I think it was really, really all over the place," Volquez said. "I threw the ball everywhere. I was talking to [catcher] Paul Bako. I'd throw my four-seamer, and that ball was like a two-seamer and started running away. I'd try to throw a two-seamer, and it would do what my four-seamer does. I don't know why."
The walks that hurt the most came when the first two batters of the Cardinals' third inning reached with free passes. That became a very unenviable position for a pitcher to be in once Albert Pujols strolled to the plate with one out.
Pujols, who walked in the first inning, was 0-for-8 in the series until he smoked a 2-1 four-seam fastball into the right-center-field seats for a three-run homer and 3-1 Cardinals lead.
"You know sooner or later, Albert is going to do something," Baker said. "We had been holding him in check the last two days."
"Wrong pitch," Volquez said. "Maybe I have to throw something in the dirt and face the next guy. It was a mistake."
The Reds kept the game close against Cardinals starter Kyle Lohse (14-6). Jeff Keppinger hit an RBI double in the bottom of the third inning, but St. Louis got the run back in the fifth on Felipe Lopez's RBI single.
The Reds notched leadoff doubles in the sixth, seventh and eighth innings, but scored only one run when Joey Votto came home on Jolbert Cabrera's seeing-eye RBI single with two outs in the sixth.
Back-to-back two-out doubles off Reds rookie reliever Josh Roenicke, including Adam Kennedy's RBI double to right field, gave St. Louis insurance in the top of the eighth. Cardinals closer Chris Perez walked two in the ninth with Corey Patterson scoring on Jerry Hairston Jr.'s bloop RBI single to short center field. Jason Motte had to finish for his first career save.
Volquez is 16-6 with a 3.29 ERA in 32 games this season, including 31 starts, and should have two more starts remaining. He is closing in on two other benchmarks -- 200 strikeouts and 200 innings. He has 197 strikeouts and 188 2/3 innings.
Over his past four starts, Volquez is 0-1 with a 4.91 ERA and just one quality start.
"I know I'm going to get it before the season is over," Volquez said of No. 17. "Right now, it's a little bit tough.