So, um, what caused the gash? Was it chainsuck or something else?

I perodically get enquiries along the lines of 'can you fix carbon?'. Makes you wonder how many of those frame are currently landfill.

I had a rear wheel lock-up once that was caused by one of the drive pawls in the freewheel snapping off, so that could be a possibility, but that didn't cause any damage to the frame. Does sound like chainsuck to me though, can't think of what else it could possibly be.