Hi Alba,
I believe it comes down to our team selections and lack of funds to be honest. Moyes continually plays players out of position, and this season (other seasons as well for that matter too) they've been shit in the roles they are forced into e.g. Osman at right mid, Heitinga in midfield, Bilyaletdinov as a winger etc. But the thing is we have no choice but to play these players out of position due to a lack of funds; even simply signing someone like Landon Donovan in the summer would have helped solve our right side of attack problem greatly, but we didn't have enough money for him.
As well after a bad start I think the morale is really down amongst the squad, hence why players haven't been performing as well as they have been known to. I think eventually we'll come good (hopefully sooner rather than later), but in the mean time it's very frustrating.
Good luck for the rest of the season mate