The Cardinals agreed and purchased the lefty's contract from Springfield on Wednesday. Fuentes arrived at Busch Stadium early Wednesday afternoon and was available to pitch against the Dodgers.
"I think it's gonna be great for both of us," Fuentes said. "I know that I can be successful at this level and pitch to a high level, and to come into this bullpen and help bridge the gap to [closer Jason Motte]. I can be that guy."
Fuentes was released by Oakland on July 11 and signed a Minor League deal with the Cardinals on July 15. Prior to pitching an inning in Double-A on Tuesday, Fuentes appeared in two games this month with Cardinals' Gulf Coast League affiliate.
Fuentes began the year as an important component of Oakland's bullpen -- posting a 2.84 ERA in 19 games through May 27 -- but was used sparingly after a handful of rough outings in June. He said he pitched himself into a trap where he could only improve if he threw more but hadn't earned enough opportunities.
But Fuentes said he's now confident after a few successful Minor League outings that he can be an asset in the late innings for the Cardinals' bullpen, which now features three left-handers. Marc Rzepczynski and Barret Browning are the others.
"I have a lot of pride, for sure," Fuentes said. "I don't really pitch with that vengeance on my mind, or that I'm trying to disprove or prove somebody wrong. I pitch to win. I'm here to pitch one inning time at a time and help this team get to the next level. That's what I'm focused on."
Fuentes doesn't see himself as a lefty specialist but said he was open to the idea if manager Mike Matheny felt that role was best suited for him. Matheny said it will take some time to figure out the best way to use Fuentes, but the manager does feel Fuentes' experience will be valuable for the younger relievers.
"I think he can definitely be an asset, talking to them about how he's faced some of the bigger left-handers in the league," Matheny said. "I know that's his makeup, too. He likes talking about the game."
The Cardinals optioned right-hander Victor Marte to Triple-A and designated right-hander Chuckie Fick for assignment to make room for Fuentes. Marte had struggled recently, allowing three homers in three innings over seven outings in July.
"He just kind of ran into a bad spot here where he was having trouble in situations," Matheny said. "So get him some consistent work and then we know that he's an asset that we can use as we go forward."