The previous administration a) tortured detainees, making it harder to prosecute dangerous terrorists; b) released bad guys while detaining good guys; and c) neglected to keep comprehensive files on possible terrorists who've been in U.S. custody for several years. As if the fiasco at Gitmo weren't hard enough to clean up.
I'm reminded of something John Cole said the other day: "The moral of this story is not the danger for Obama going forward with his Gitmo decommissioning, the moral is that when venal, shallow, small men are given unfettered power and authority, they do incompetent, stupid, and evil things."