I don't know that I'd quite call a 25 year old with only 13 IP in AA a "nice prospect," but it's always better to get something rather than nothing for a guy you're about to cut loose. (Or worse, to keep a guy who's out of options on the ML roster even though he sucks, just because you don't want to lose him for nothing. I'm looking at you, Scott Thorman.)
Looks like Darrow's got good control, at least. Maybe he'll end up being a useful spare part for the bullpen.