Andersen went with the Bret Bielema existing defense last year and then lost most of the accomplished front 7 from last year including Beau Allen from MN.
This year, at least when I have seen them, they are running a lot of oddball defenses, the resemble 3-4 or 2-6 fronts with a lot of undersized, but athletic guys moving all over the place. This type of defense tends to confuse the O line. A very talented LSU team with speed had a very difficult time dealing with the UW defense, so regardless, of the limitations, it to tends to work.
Aside from the O line issues, the QB might be confused by this D scheme as well.
Not very many teams play this type of defense, but I equate it with a basketball team that runs the floor with a bunch of fast quick under 6'6 players that outflank the big, slower teams that are not used to the match up, and floor running challenges seen once a year or less.