They have posted a 5-6 record since the blockbuster deal in which they landed Adrian Gonzalez and Josh Beckett, and as a result they find themselves trailing the Cardinals by 1 1/2 games in the National League Wild Card race and the Giants by 4 1/2 games in the NL West.
On Wednesday they'll be looking to cut into those deficits by winning the rubber match against the Padres, who send southpaw Clayton Richard to the mound.
The calendar may have flipped to September, but Richard is hoping his results Wednesday are similar to the stellar August numbers he put up. He went 5-1 last month, with quality starts in all five victories.
That's nothing new for Richard (12-12, 3.74 ERA), who has posted 17 quality starts this season. His 190 1/3 innings pitched were the third most in the NL heading into Tuesday's games.
In his last start, Richard managed to tame Coors Field by inducing 13 ground-ball outs, though he did allow two late homers (three runs total) in 6 1/3 innings.
"I didn't quite execute late in the game as much as I did early," Richard said after the start. "I think it cost me from going deeper in the game."
Right-hander Aaron Harang gets the ball for the Dodgers, facing his former team, against whom he is 1-1 with a 3.65 ERA in four starts this season.
Harang (9-8, 3.76 ERA) was bitten by a stroke of bad luck in his last time out, when he gave up a run on a fly ball lost in the lights. He earned a no-decision in five innings of three-run ball.
Padres: Four added to roster
On Tuesday, the Padres added four players to their roster: catcher Ali Solis, infielder Andy Parrino and pitchers Brad Boxberger and Anthony Bass.
Parrino, Boxberger and Bass have all seen time in the Majors before, but when Solis sees his first action this season, it will mark his first big league game.
"What a great story," said Padres manager Bud Black, noting Solis' journey from when he signed with the club as a 16-year-old out of Mexicali -- located two hours east of San Diego.
The team designated catcher Eddy Rodriguez and pitcher Ross Ohlendorf for assignment to create room on the 40-man roster for Solis and Bass, who had been on the 60-day DL.
Dodgers: Bullpen shakeup
The Dodgers received plenty of news regarding injuries in their bullpen on Tuesday, and not much of it was good.
Closer Kenley Jansen, who has been sidelined because of an irregular heartbeat, will miss another two weeks because he won't be able to come off his blood-thinning medication for another 10 days.
"Keep my mind positive and stay ready so whenever I'm off the medicine, I'm ready to roll again," said Jansen, who was initially hopeful to be back for this weekend's critical series against San Francisco.
Righty reliever Javy Guerra, who figured to play a larger role in Jansen's absence, was placed on the DL with a strained left oblique muscle, retroactive to Sept. 3. Right-hander Josh Wall was recalled to replace Guerra.
Matt Kemp and Andre Ethier have fared quite differently in their careers against Richard. Kemp has 10 hits -- five for extra bases -- in 27 at-bats for a .385 average, while Ethier is hitting just .120 on three hits in 25 at-bats.
In 37 career games at Dodger Stadium, Headley is hitting .331 with a .404 on-base percentage.
The Dodgers are 4-5 on their current stretch of 15 consecutive games against division opponents.