SAN DIEGO -- Division-clinching is the main storyline for the Dodgers on Tuesday night, but Chad Billingsley is no minor subplot.

It's not often that a team's leading winner two years running uses his last regular-season start to determine his role in the playoffs, but that's the situation for Billingsley, as unthinkable as it might have been three months ago.

Pulse
Dodgers at a glance
2009 record: 95-67
2008 record: 84-78
NL West champs
NL best record
NLCS matchup:
Phillies at Dodgers
Postseason tix: Buy now

WHO ARE THESE GUYS?
Loney: Taking good swings
Kuo: Long road back
Thome: Back in Philly
Loney: Building resume
Bullpen: Led by Broxton
Torre: Rep precedes him
Blake: Chemistry guy
Kershaw: Game 1 nod?
Dodgers: Eyes on prize
Kemp: Path of the pros
Furcal: Back healthy
Kershaw: Like Koufax
Hudson: Keeping head up
Billingsley: Unknown role
Ethier: Slump over
Torre: Tough decisions
Kershaw: Elite comparisons
Kemp: Nearly elite
Kershaw: Path to the pros
Billingsley: Fate in balance
Ethier: Aims to improve
Torre: Back to playoffs
Kershaw: Ready to rock
Rotation: Plenty of options
Kemp: Chasing LA history
Bullpen: Dominant pair
Honeycutt: Pitching guru
Kemp: Tools to match talent
Ethier: Walk-off wonder
Billingsley: Vying for spot
Ethier/Kemp: Dynamic duo
Torre: Another pennant race
Pierre: Receives high praise
Kershaw: Beyond his years

Coming off a 16-win season, Billingsley was the staff ace and All-Star who started this season 9-4. Since then, he's 3-6 with a 5.42 ERA and trying to make the cut as the Dodgers reduce a six-man rotation to four.

Billingsley will be facing the Padres coming off a start in Washington that rolled his two seasons into one game -- a no-hitter through five innings, then a pair of walks and a three-run homer by Ryan Zimmerman on a hanging breaking ball.

Manager Joe Torre was asked if the first five innings of that start are more representative of Billingsley's current state than the sixth inning.

"I hope so," Torre said. "There was more positive than negative from that game. He said he made one bad pitch. I don't agree -- it was the walks. But he wasn't wild, he was just trying to be careful. When he's efficient, as he was, maybe he feels he can do things, make the perfect pitch. He's been a horse for us, so I don't think he got tired."

Billingsley hasn't won a game in almost six weeks, his last victory coming Aug. 18 against the Cardinals. Because of that win, if the Dodgers open against the Cardinals, it improves Billingsley's chances of joining Randy Wolf, Clayton Kershaw and Hiroki Kuroda as the fourth starter instead of Vicente Padilla or Jon Garland. His problems against Philadelphia in last year's playoffs -- 10 earned runs in five innings -- are well-documented.

Billingsley and pitching coach Rick Honeycutt agree on what went wrong this season. Comparing game videos frame by frame, Honeycutt noticed that Billingsley's mechanics began changing July 10 in Milwaukee, the last start before the All-Star break.

"His arm path was drifting behind him, and almost as a counterbalance, his head started going toward third base and it was creating a cross-fire," said Honeycutt.

"Then he overcorrected and got his arm slot higher and it was a domino effect of bad habits. And he got frustrated, and that's where the mental side comes in. Chad expects a lot of himself and he's hard on himself. He's always battled through things like this, but maybe he had a stretch with a lack of confidence and tried to do too much. You can only produce what you have."

Billingsley admits to the frustration. He moved from the third-base side of the rubber to the first-base side. Now he's back to the third-base side.

"You try to correct one thing," he said, "something else happens. That's frustrating. You do this, you do that to figure something out. I had a hard time throwing away to left-handed hitters, tried to force it there and everything got thrown off. Now I'm just trying to simplify everything in my mind."

And it led to his last start.

"I had command of the fastball and the offspeed. I haven't had a lot of those days lately," he said. "I was consistent down in the zone. It was a good start with a lot of positives and I can build on that. I want to get into the same type of game plan in San Diego."