This President is the worst negotiator in American history, just like the Taliban got their high command restored for the release of a deserter, the Castro's got three valuable convicted spies for an aid worker, and no other concessions.
This is not the kind of "negotiation" you are thinking of. It comes down to, "We've been enemies for 50+ years, it sucks, let's make friends; first step, we'll release all of your people we're holding and vice-versa." An indispensable first step, and the head count is irrelevant.