One, it's never made any sense for the Yankees to keep both Cabrera and Gardner on the 25-man roster. Gardner offers defense along with maybe the ability to reach base, while Cabrera offers little defense and just maybe the ability to hit for some power, someday. Gardner bats left-handed, while Cabrera's a switch-hitter who has (to this point) fared particularly poorly against left-handed pitchers.
Two, if you're going to get rid of one of them, Cabrera's probably the guy. At least Gardner's demonstrated that he can do something (run and field) and might do something else (reach base). At this point, it's not clear that Cabrera can do anything. And I say that, having written -- just two or three years ago -- that by now Melky would be one of the 10 best center fielders in the majors (not one of my more brilliant predictions).