Robertson struggled this season with Florida, posting a 5.47 ERA and 1.495 WHIP in 19 appearances, 18 of them starts.
Although it is doubtful the Cardinals would call Robertson up as a starter with the recent addition of Jake Westbrook, and Kyle Lohse close to returning, he could be used as a left-handed specialist out of the bullpen. Currently, lefty reliever Dennys Reyes has posted a respectable 3.00 ERA this season, but has a 1.333 WHIP and is walking 5.1 batters per nine innings. After starting the season with a 0.54 ERA in 25 games, Reyes has been shelled for a 6.39 ERA in his past 22 games.
Cardinals manager Tony La Russa dismissed the notion of inserting Robertson into the bullpen, however.
"Well, he is really not a left-handed reliever, that is the one thing," La Russa said. "You know, he has made a career pitching against right-handed lineups."
Robertson has had substantially more success versus lefties in his career, though. Right-handed hitters have posted a career .829 OPS, while left-sided hitters are significantly lower with a career .694 OPS.