I see a trend, Games without multiplayer have a big opening week but rarely have legs, (Heavy Rain as an exception) and Games with multiplayer have a modest or sometimes very strong opening week and have great legs. (Games with an established userbase tend to have both a strong opening week and strong legs i.e. Halo)
It makes alot of sense because the ones with multiplayer have far better replay value
Because MNR has Multiplayer, a very deep multiplayer at that, and I believe it will outsell Alan Wake, which doesn't have Multiplayer.