Colletti searching for missing piece

General Manager Ned Colletti isn’t optimistic he will be able to make any significant acquisitions before the Aug. 31 deadline for setting playoff rosters, meaning the Dodgers will probably have to continue their battle for a postseason berth with the team they have.

That hasn’t been for a lack of effort, Colletti said. The team has made approximately 40 waiver claims in the last three weeks, he said, but the players he was interested in either had their waivers withdrawn or were claimed by other teams.

“We’re trying to find that piece,” he said. “If it makes sense we’ll do it. [But] the list of available players who have cleared waivers doesn’t present us with a lot of opportunity or intrigue.”

With the Dodgers missing two frontline starters, Colletti said his focus has been on acquiring pitching but added that “anybody that will make us better we’re interested in.”

Last summer Colletti traded for right-hander Greg Maddux at the July 31 nonwaiver trade deadline and added utilityman Marlon Anderson on Aug. 31; both played key roles in getting the team to the playoffs. This year Colletti acquired reliever Scott Proctor at the July trade deadline, then got pinch-hitter Mark Sweeney from the Giants and signed Shea Hillenbrand, who had been released by two clubs, in the last week.

Tony Abreu’s return to the active list -- and the lineup -- at triple-A Las Vegas this week doesn’t mean the Dodgers and the infielder’s agent have reached agreement on when the player was hurt.

Colletti declined to discuss the matter in detail Thursday but Scott Boras, who represents the player, said “after examination, two physicians determined he suffered an injury while in the major leagues and was unable to play until Aug. 14.”

Abreu sustained what was originally termed a strained abdomen while playing for the Dodgers early last month but wasn’t placed on the disabled list until after he was optioned back to the minors. The timing of the move cost Abreu tens of thousands of dollars in salary as well as valuable major league service time and Boras could file a grievance with the players’ union if the two sides can’t reach a settlement.

A similar dispute between the Marlins and pitcher Anibal Sanchez led to a grievance being filed on behalf of Sanchez, who says he was demoted to the minors despite a shoulder problem that led to season-ending surgery in June. The demotion is costing Sanchez more than $1,400 a day in salary, according to union attorney Jeff Fannell.

Colletti said the dispute won’t affect Abreu’s future with the organization. The 22-year-old Dominican could be recalled when major league rosters expand Sept. 1.

Left-hander Hong-Chih Kuo, on the disabled list since June 30 because of an inflamed shoulder, has begun throwing again and left-hander Randy Wolf, out since July 4 because of a sore shoulder, is expected to begin throwing again on the trip that begins Tuesday in Philadelphia.

Jeff Kent doubled three times Thursday, giving him 530 in his career, which moved him past Al Oliver for 28th on the all-time list. . . . Outfielder Andre Ethier and broadcaster and former Dodger Rick Monday are scheduled to sign autographs at the St. Vincent de Paul Thrift Store at 210 N. Avenue 21, in Lincoln Heights just north of downtown, from noon to 2 p.m. today.

Times staff writer Dylan Hernandez contributed to this report.

kevin.baxter@latimes.com