It turns out individuals we've held at Guantanamo and released are causing trouble for us after being released. See this Washington Post article. Recidivism? Yes, it says we were holding the right guys after all.
The major question is why they were released. I cannot fathom why we don't call them prisoners of The Long War who will be released when the war is over, if it ever is. If we planned to keep them until hostilities are over, probably most would die of old age before hostilities cease. We know turning them loose doesn't work, so keeping Guantanamo open and them in custody makes sense.
