Mujica is 9-for-9 in save opportunities heading into Friday's series opener against Colorado. He sports a 1.93 ERA with 14 strikeouts in 14 innings covering 14 appearances.
"He just goes out there with confidence on every pitch," said former closer Jason Motte, who underwent Tommy John surgery on Tuesday. "He knows what he wants to do."
Mujica, who was acquired by St. Louis for Zack Cox on July 31 of last season, received some shirts as a birthday present from his wife Erika and daughter Brianna.
Plus, Mujica was expecting a cake when he got home late Friday night.
"There's not much time to do anything," he said. "Not a big deal."
Steve Overbey is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.