Strange formation?

I just played a match against a Ligue 1 team and this is the formation they used the whole game. I have never seen anything like it and frankly, it just seems utterly foolish to use that kind of formation, especially when I was using 4-4-2 with attacking wingers. Any thoughts?

They've had a player sent off..

You mean the fact it was a narrow diamond? Doesn't seem entirely strange when you consider they had 5 at the back. When was their player sent off?

I find the AI uses some very strange formations after a sending off.

I used a very odd formation one match, I usually like to use the 4-2-3-1, but I was using a rubbish youth team left-back, and wanted to give him some protection, so I went for:

GK; DL, DC, DC; WBR, DM; ML, MC; AMR, AMC; FC

Looked like this:

------------FC-------------

-------AMC------------AMR

ML------------MC----------

--------DM------------WBR

DL------DC-----DC---------

------------GK-------------

You mean the fact it was a narrow diamond? Doesn't seem entirely strange when you consider they had 5 at the back. When was their player sent off?

He was sent off after 26 minutes. And their starting formation was 4-2-3-1.

---------x---------

---x-----x-----x---

------x-----x------

-------------------

---x---x---x---x---

-------------------

Not strange at all. It is the end of the game, they are losing 4-0 already, the have a player sent of and they are trying to keep the score "low". What else could the do?!