The swap gives the Cardinals an extra arm in the bullpen for the next few days, and opened up a place in the rotation for Garcia. Lyons was winless in three spot starts for the Cardinals, the most recent a 3 2/3-inning effort in a loss on Saturday.
Since Adam Wainwright tore his left Achilles, the Cardinals have gotten insufficient results from his replacements. Lyons and Tim Cooney combined to allow 25 hits and 11 earned runs over 15 1/3 innings (four starts). Now, it will be Garcia's turn to try and stabilize the back end of the rotation.
"First of all, just to be here and have an opportunity to be back in this clubhouse with my teammates, it's something that I'm just extremely grateful for," said Garcia, who returned to St. Louis after making a quality start with Double-A Springfield on Friday. "I know it's been a long road, but I'm extremely excited to be here, and I'm definitely looking forward to pitching on Thursday."
Garcia's start will be his first since undergoing thoracic outlet surgery last summer. Various shoulder injuries have limited the lefty to 16 starts since 2013. He was poised to win a rotation job out of Spring Training until his shoulder stopped responding well. He has been slowly rebuilding arm strength since.
"He's been very clear that he's been feeling much stronger [than he did in Spring Training], and he has an ability to respond after he throws," Mozeliak said. "Getting his pitch count up was critical, but clearly, right now, we need someone to step up and take that fifth spot. He'll get that chance."
With Lyons and Cooney mostly unimpressive in their chances with the Cardinals, Garcia and Marco Gonzales, who has struggled in his most recent pair of Triple-A starts, represent the club's best internal options to fill the innings void left by Wainwright. How Garcia fares will shape whether the club has to seek starting help elsewhere.
"Let's give him a chance to see if he can be that answer," Mozeliak said. "Clearly starting Thursday, he'll get that opportunity. … We have to be thinking that if we can't do it from within, then we may have to look externally. But we're not at that point where we feel we have to do something just to do it."
With Tuivailala up, the Cardinals will stick with a nine-man bullpen until after Wednesday's game, at which time Garcia will be added to the roster.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, follow her on Twitter @LangoschMLB, like her Facebook page Jenifer Langosch for Cardinals.com and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.