Robertson struggled this season, posting a 5.47 ERA and 1.495 WHIP in 19 appearances, 18 of them starts.
Although it is doubtful that the Cardinals will call Robertson up as a starter, as they have a surplus of arms available, he could be used as a left-handed specialist from the bullpen. Lefty reliever Dennys Reyes has posted a respectable 3.00 ERA this season, but he has a 1.333 WHIP and is averaging 5 1/3 walks per nine innings. After starting the season with a 0.54 ERA in 25 games, he has been shelled for a 6.39 ERA in his past 22 games.
Robertson has appeared in only 34 games as a reliever in his career, and he has a 7.25 ERA from the bullpen.
Michael Bleach is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.