Fuentes was designated for assignment and then released by the A's earlier this month after a disappointing start to his season. In 26 appearances with Oakland, Fuentes allowed 30 hits and 19 earned runs in 25 innings.
The Cardinals, however, have been searching for left-handed relief help since releasing J.C. Romero in May. Right now, rookie Barret Browning is serving as the club's second lefty, behind Marc Rzepczynski.
Fuentes is believed to be mulling various offers, leaving the Cardinals to wait for that decision. Fuentes, 36, is just three seasons removed from his fourth All-Star appearance, and is coming off a season in which he posted a 3.70 ERA in 67 games.
Signing Fuentes would not come at a substantial risk for St. Louis. Because Fuentes was released, it's the A's who are on the hook for paying the rest of the $6.5 million Fuentes is due from his 2012 contract. A team could sign him now for as little as the prorated minimum Major League salary.
The Cardinals' search for bullpen upgrades won't end with Fuentes, even if he signs.
"I would say that our interest in right-handed relief is high," Mozeliak said. "Basically, when you look at our bullpen, we're happy in the eighth and ninth. We just have to get from the starter to there. If you look at the landscape of the trading market right now, getting a reliever might be easier than getting a starter."
The organization would love to add a starting pitcher before the July 31 non-waiver Trade Deadline, but the supply is low and the demands are currently too high. Offseason changes with the Draft pick compensation rules will affect what the Cardinals are willing to give up for a short-term boost, as well.
Teams that acquire a player midseason are no longer eligible to receive a compensatory Draft pick if that player ends the season with Type A or Type B status. In the past, clubs have given up top prospects knowing that if the player it acquires ends up walking away as a free agent during the next season, the organization will at least be in line to get a Draft pick or two in return.
With no such cushion in place, the Cardinals are not willing to trade away their most valued prospects for a player who is not signed beyond this year.