Both Salas and Rzepczynski were called upon to pitch more than an inning in Monday's 9-2 loss to the Pirates. Salas threw 35 pitches in his appearance, and Rzepczynski needed 20 to get four outs. By adding Blazek and Butler to the 'pen, the Cardinals are assured of having seven available relievers on Tuesday.
"Both have been throwing well," manager Mike Matheny said. "They did a nice job when they were here. We weren't getting them a lot of work, but we'll probably need their help this time."
This will be Blazek's third stint with the Cards this season. He was most recently sent to Triple-A on July 10 after allowing three runs in three innings (four appearances). Butler followed him to Memphis five days later and has pitched four times since. Both righties are plenty fresh, too. Blazek last pitched on Saturday; Butler's most recent appearance came last Friday.
Salas and Rzepczynski combined to allow five seventh-inning runs to the Pirates on Monday. The outing was Rzepczynski's second since being recalled after a near three-month stay in the Minors. He pitched a scoreless inning on Sunday in his first appearance back.
In removing Rzepczynski from the roster on Tuesday, it became evident that his time with the Cardinals was limited. Rather than waiting to non-tender him over the winter, the Cards were able to deal the left-hander now and get a player in return. They also receive some salary relief, as Rzepczynski is in the middle of a one-year, $1.1 million deal.
Salas had been scored upon in three of four appearances since rejoining St. Louis after a stay on the disabled list and a stint in the Minors. Overall, he has a 4.79 ERA in 19 appearances for the Cards this season.
Salas, like Rzepczynski, has not been the same pitcher since 2011. His time with the organization may be winding down, too, as Salas will be arbitration-eligible at the end of the season.
"It's tougher for them to have to go through," Matheny said of the demotions. "We get that, but we have a tough assignment here with a lot of games and not many days. We have to put our best foot forward."
The Cardinals are seven games into a stretch that has them playing 37 games in 37 days.
At the same time these two roster moves were announced, the Cardinals also made official the addition of Tyler Lyons. He was added to the roster as a 26th player for the day. Beginning last year, Major League Baseball approved expanding the active roster by one for doubleheaders scheduled at least 48 hours in advance.
Lyons will start Game 2 for the Cards on Tuesday and will be opposed by Pittsburgh's Brandon Cumpton, who has also been called up from Triple-A.