It's Simply Games, they try and make everything drop super quick. It was where I got my PS4 FIFA 14 from a week after the console launch for the same price.
If more retailers follow suit, I'll agree that they may have ordered too much stock in.
EDIT: Am laughing that the last-gen versions are more expensive now though.
It's still too quick especially for next-gen versions. Last gen there was always great deals from supermarkets, Amazon price match on day 1 but online retailers never dropped the price of a new COD by 10 pounds 4 days after launch.
To me this sounds like they are afraid bad reviews from big sites will kill the legs of the game instead of this becoming a Christmas wishlist product like it was predicted to be.