Confused about this DK tanking build.

I was wondering around dalaran today and got confused over a DK tank I inspected. I have never seen this sort of tank build before and i wonder if someone could shed some light on it.
Looking at the build i couldn't figure the rotations or the need for Scent of Blood as a blood tank.
http://www.wowhead.com/talent#jMEGV0...LhxLZcx:0GiVMc

I see a lot of tanks with faceroll specs. It's disturbingly common even in raiding guilds.

It's just some random spec, nothing you should worry about. My guess is that the guy doesn't know what he's putting his points into.