Cardinals relievers were 10-18 with a 4.25 ERA and 18 blown saves in 43 chances entering a four-game series against the Mets on Monday night. They'll carry 13 pitchers and 12 position players for the foreseeable future.
Outfielder Nick Stavinoha, who batted .250 (4-for-16) in five games with two RBI, was optioned to Memphis.
"We've got some fried relievers," manager Tony La Russa said. "We're playing seven games without a day off and we've got guys we don't want to send out there when they shouldn't pitch."
Jason Isringhausen, working his way back to the closer role, is wearing a brace on his right knee that allowed him to avoid being placed on the 15-day disabled list over the weekend. Mark Mulder was activated from the DL on Friday as a reliever for the first time of his career and La Russa said he'd like to use the left-hander at the start of an inning.
Thompson was 1-2 with a 4.37 ERA in seven games, three of them starts. He was optioned to Memphis on June 20, the day after he allowed two runs in five innings and took the loss against the Royals. That was his only appearance after being activated from the DL (elbow) the day of that start.
Thompson made one appearance with Memphis after being demoted, allowing four runs and nine hits in four innings on June 24. His scheduled start for Sunday was pushed back one day before getting the call from the Cardinals.
La Russa said Thompson is not a candidate for the rotation at this point and confirmed that rookie Mitchell Boggs, 3-0 with a 4.37 ERA, would make his fifth career start on Thursday against the Mets.
Mulder warmed up on Sunday but was not used. La Russa said Mulder can be much more than a second lefty in the bullpen along with Ron Villone given his impressive record before undergoing a pair of shoulder operations.
"He was one of the outstanding starters and he faced mostly right-handers," La Russa said. "I think he can pitch against anybody when he's right."