I can see where you're coming from, but I don't agree.
Marte, if not given a physical would not really hurt the Red Sox that bad. Marte's injury problems are just rumors, and nothing's been confirmed. Throw in the fact, that he's 21, has a world of potential, and with our advances in medical science, sitting out a year wouldn't hurt the Boston Red Sox that badly.
Mota, however, is a major league ballplayer making a pretty good chunk for a middle reliever. Being a middle market team like the Guardians, I'd be extremely wary of pulling the trigger on an injury prone middle reliever, whom I'm happening to be paying 3 million for.