LOS ANGELES -- Odalis Perez's balky shoulder has forced the Dodgers into a series of staff decisions.
Perez, re-signed to a three-year, $24 million contract earlier in the year, will be placed on the 15-day disabled list, the team's 10th disabling injury this year. Veteran Wilson Alvarez will start Wednesday night in San Francisco. Scott Erickson will move into the bullpen.
Manager Jim Tracy would not commit as to who would start in Arizona on Saturday, the next time a fifth starter is needed. A possible candidate is rookie D.J. Houlton, although he has not pitched longer than two innings in any of his 11 relief appearances.
Nor would Tracy say who would replace Perez on the 25-man roster. Logical candidates are Triple-A relievers Steve Schmoll and Buddy Carlyle.
Perez has inflammation in the front of his shoulder. His bullpen session set for Sunday was scratched because he still had discomfort during a Saturday game of flat-ground catch. Perez is 4-4 with a 4.50 ERA and his inability to face the Giants is a disappointment, because he's already 2-0 against them this year after going 2-0 last year.
Perez has not pitched since he left a May 14 loss to Atlanta after six innings.
Perez was unable to make his Friday night start and was replaced by Erickson, who couldn't get past the second inning. One of the finest inning-eaters of the 1990s, Erickson made the club in Spring Training as a starting pitcher, but has struggled to a 1-4 record and 7.22 ERA, not reaching the fifth inning in four of eight starts.
In 14 seasons, Erickson has relieved in only five games and Tracy said he will be mindful of Erickson's ability to warm up quickly and bounce back between outings.
"We've seen very good starts from him against Washington and Atlanta, and very erratic in between, like night and day," said Tracy. "He's gone through the lineup one time pretty good. He took it terrific. He totally understands it."
The injury to Perez, Erickson's inconsistency, the uncertain condition of Jeff Weaver's shoulder and the late start to the season of Brad Penny have all been factors in the generally disappointing performance of a starting rotation that eats up the bulk of the Dodgers payroll.
Drew, Choi switch: Tracy tried to shake up the lineup Sunday by moving slumping J.D. Drew from third to second in the batting order, with Hee-Seop Choi dropping from second to third.
"I just feel like trying different things," said Tracy. "Am I totally certain it's going to work and be the key that unlocks the safe to get the guy going? I'm not that smart to know that. I've seen it before, giving a guy a slight environment change helps the situation."
Hee Seop Choi / 1B
Weight: 240 lbs
Bats: L / Throws: L
Drew has been a disappointment after signing a $55 million contract. He's batting .246 with five home runs and 16 RBIs, while Choi has come alive to hit .308 with six homers and 18 RBIs in 38 fewer at-bats than Drew.
"I think it's a good idea," said Drew. "I think it's good to change every now and then. See how it works."
Drew said his difficulties have been compounded by bad luck, including hard-hit balls at fielders and borderline pitches called strikes.
"When you have borderline pitches go against me, I tip my cap and move on," said Drew, who is known to have a disciplined eye at the plate. "I can't become some kind of crazy free-swinger at every pitch. I'm not a Vlad Guerrero hitting off my shoe tops. I have to stay with the same approach, that's for sure."
Injury update: Elmer Dessens had a 45-pitch bullpen session, using all of his pitches, but he is still a few more bullpen sessions away from a Minor League rehabilitation assignment.
Jason Grabowski, disabled with a shoulder impingement, begins a Minor League rehabilitation assignment Monday with Triple-A Las Vegas.
LaRoche hot: Class A Vero Beach third baseman Andy LaRoche, brother of Atlanta Brave Adam LaRoche, hit two home runs Saturday to give him 14 and he leads the Florida State League with a .354 average. He is a likely candidate for promotion.
Coming up: After a day off Monday, the Dodgers travel to San Francisco for a three-game series with the Giants, opening Tuesday night with Weaver starting against Jason Schmidt. Weaver has admitted to a dead-arm of late.
ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.