When the Tigers designated Armando Galarraga for assignment, it was pretty clear his time with the team was over. Obviously he wasn't going to clear waivers because he's the sort of pitcher who you could pencil in the #5 spot in about half the rotations in baseball. Someone would've made room for him.
Of course, his status as a capable back-end starter also gave him value as a trade target for any of the teams that would've placed a waiver claim. Despite my vehement opposition, Tigers GM Dave Dombrowski clearly felt as though the options he had internally, be it Andrew Oliver or Charlie Furbush, would be adequate in the event that one of his five opening day starters became injured or proved ineffective. And so Galarraga immediately became trade bait.