18 minutes ago (at time of writing) a whole swathe of questions appear to have been deleted, some of which seemed not to be obviously sub-par or off-topic, and some of which had a net rep scoire of 0 (in contrast to some things deservedly on around -5 which have been hanging around in the delete queue for some time).

How is the system making these decisions? Something like http://mathoverflow.net/questions/150219/monotone-parabolic-systems-convex-variational-structure-and-legendre-transform should in my view be undeleted; but my main question is as to why the system has suddenly kicked in and deleted all these questions in one go?