I would use 3-1-4-2 but I've never played against that formation before so don't bank on it.
Either that or the 4-1-2-1-2 diamond could possibly work too.. Again, this is just an educated guess. It's what I would use if I was against it.. Wait for more answers to confirm
It would help if they did a bit more homework first.
Those DM's could be doing anything.
Goals scored by them is usually a good indication as to how he plays them.
Played against it a few time a few seasons ago in the CL
I played 3N-2N-2W-2N-1