Unfortunately, Ledezma proved to be more effective when working over long stretches as opposed to just facing one or two batters, and didn't prove to be particularly adept at getting left handed hitters out, with lefties hitting .340 against Ledezma.
The Tigers needed better out of a lefty setup man, and with Ledezma out of options, the Tigers needed more roster flexibility. That's part of what they got in Macay McBride.
McBride had two characteristics that the Tigers loved and felt it was worth it to move Ledezma, who the organization still thought could be a very good pitcher. One, his average against lefties is an impressive .160. And two, he still has options remaining, so if the Tigers get into a numbers crunch in their bullpen, McBride gives the team the flexibility of moving him down to Toledo without having him go through waivers.
At the moment, the Tigers haven't made a final decision as to who will move down, but the Tigers now have the option of sending of McBride down as well, even if it's only temporary.