Just when the Pirates rotation appeared to resemble a five-man unit, it returned Thursday to its general state of confusion.
A.J. Burnett was put on to the 15-day disabled list Thursday, retroactive to Sunday, because of a strained right calf. The Pirates also released Jose Contreras.
The moves cleared room on the active and 40-man rosters for Charlie Morton, who officially was added to the roster about an hour before he made his comeback from Tommy John ligament replacement surgery.
In Burnett's most recent start, he pitched 81/3 innings of two-run ball against the Chicago Cubs.
"He made us aware of it [Wednesday]," manager Clint Hurdle said of Burnett's calf pain.
Jeff Locke, originally scheduled to start Saturday, will start instead tonight against the Los Angeles Dodgers in place of Burnett. Locke will pitch on his usual rest instead of getting an extra day between starts.
Contreras was on the 15-day DL because of lower-back pain. The Pirates signed him as a non-roster invitee in spring training, while he was rehabilitating after Tommy John surgery. He allowed five runs and six walks in five innings.
The Pirates have not announced who will start Saturday. Right-hander Brandon Cumpton is scheduled to start Saturday for Class AAA Indianapolis but is not on the 40-man roster. Indianapolis' scheduled starter Friday, left-hander Andy Oliver, is on the 40-man and could be pushed back a day.
More action for Mercer
Jordy Mercer started at shortstop for the second consecutive night after going 3 for 5 Wednesday.
"I think if you keep showing up and you keep an eye on that lineup out there, you'll be able to read into what we're going to try and do," Hurdle said. "We're not quitting on anybody. We're not putting anybody aside. There will be appropriate times for everybody to still stay engaged."
Clint Barmes had a .235 on-base percentage and .270 slugging percentage to go with 38 strikeouts and five walks before Thursday. In about half as many at-bats, Mercer had a .296 OBP and .494 slugging percentage.
"Neal [Huntington] and I talked and I shared with the staff, if we're going to keep the young man here, the young man's got to play," Hurdle said. "He's got to develop here."
Marte out of lineup
The Pirates removed Starling Marte from the lineup before the game Thursday night against the Giants because of pain in his rib cage. Alex Presley batted leadoff and played left instead of Marte.
Tabata makes some progress
Jose Tabata, on the DL because of an oblique strain, is running and throwing, Hurdle said. Tabata also is swinging the bat again.
"Swing progression, the tee and some flips first," Hurdle said. "Then, some soft toss, then he'll go live arm and then he'll go machine velocity."
Tabata is tentatively scheduled to begin a rehabilitation assignment June 21.
Puig rare bright spot for L.A.
Not much has gone right this season for the Los Angeles Dodgers, who will open a three-game series against the Pirates Friday and were last in the National League West Division before games Thursday despite a $214 million opening-day payroll. But Yasiel Puig has been a recent bright spot. This 22-year-old Cuban outfielder hit .486 with a .514 on-base percentage and an .886 slugging percentage, including four home runs, in his first 10 games.
Bill Brink: email@example.com and on Twitter @BrinkPG. First Published June 14, 2013 4:00 AM