ST. LOUIS -- The Los Angeles Dodgers clinched their first NL West title since 2004 before taking the field, thanks to three consecutive disappointing losses by the Arizona Diamondbacks.

Arizona was only two games out with six games to play. The defending division champions bowed out quietly in a 12-3 rout by the St. Louis Cardinals on Thursday.

"It was just disgusting," Conor Jackson said. "It was embarrassing. You can't pitch, you can't hit, you can't win games."

Arizona (79-80) led the division by 4½ games before play on Aug. 29, then lost 11 of 14 as the Dodgers took control of the division. The Diamondbacks had rebounded by winning seven of eight to put the heat on the Dodgers, but began to fade Tuesday when the Cardinals scored four runs in the first inning off Randy Johnson in a 7-4 final.

"They hit a hot stretch, and we hit a cold stretch. Put that together and you get the Dodgers jumping around right now," Chris Snyder said.

Albert Pujols hit a three-run homer and finished with four RBI to back Joel Pineiro (7-7), who yielded three runs and three hits over seven innings on his 30th birthday. St. Louis had been eliminated from postseason contention on Tuesday.

"You had an obligation to play like we've been playing all year," manager Tony La Russa said. "It's not enjoyable at all, but you have to compete."

Arizona third baseman Mark Reynolds set a major league record with two more strikeouts, raising his season total to 201. Philadelphia's Ryan Howard set the previous mark of 199 last year -- and Howard began the day with 196 this season.

"It's obviously something I have to work on for next year," said Reynolds, finishing his first full year in the majors. "Of course, it's not the greatest of records to have, but you move on. A lot of young guys struggle."

Reynolds has 34 errors and could become the first player to lead the majors in errors and strikeouts since Minnesota Twins shortstop Zoilo Versalles (122 strikeouts, 39 errors) during his 1965 AL MVP season. Reynolds is having a nice year even with the strikeouts with 28 homers and 96 RBI, although he's batting .240.

The Diamondbacks led by as many as 6½ games in April while going 20-8. The rest of the season, they've struggled for consistency.

"Obviously, it hasn't been the type of year we expected," Melvin said. "After the first month we couldn't put together any kind of an extended period that resembled the team that played in the first month.

"The expectations get raised and you don't follow through."

Pujols (35) and Ryan Ludwick (36) hit consecutive homers in a five-run seventh that opened an 11-3 lead. Troy Glaus walked four times to match his career high, and Felipe Lopez had three hits and two RBI.

La Russa endorsed Pujols for the NL MVP earlier this week, adding he didn't think anyone else was close.

"Whatever he ends up with, he's had a monster season," La Russa said.

Pineiro matched his season best with seven strikeouts after going 0-2 with an 8.40 ERA in three previous September starts.

"It's a nice way to go out," Pineiro said. "You kind of wish you had more starts like that early in the year to try to help the team out a lot better."

St. Louis had 17 hits and nine walks against Doug Davis (6-9) and five relievers. The three-game winning streak follows a slide of 10 losses in 12 games that knocked the Cardinals out of the Central race.

Notes

• Pineiro struck out twice and sacrificed, leaving him 5-for-51 (.098) at the plate with 35 strikeouts. He had three doubles and four RBI.
• Glaus' four-walk game was the second of his career, the first since June 9, 2001, against the Dodgers.
• The Cardinals have hit back-to-back homers six times this year, the last two times off Yusmeiro Petit. Yadier Molina and Lopez connected off the right-hander on Sept. 2 in Arizona.
• SS Cesar Izturis was 9-for-13 in the series and finished 13-for-25 (.520) against the Diamondbacks, and Lopez was 16-for-31 (.516).
• Melvin said Chad Qualls, the Diamondbacks closer the last few weeks, would begin spring training in that role.