I think what people are all up in arms about when relating BF3 to being 'COD clone' or what have you, is the fact that on almost every single public server you get into- more and more people are just doing whatever they want all by their lonesome instead of taking the initiative as a squad member or team mate to make the round a win for the whole team.
I think that leads to the whole COD thing. They're not the same at all, but a lot of idiots run-and-gun-like-an-arcade-fun in true COD style.
I despise the senselessness you get on a lot of public servers, whether it be rush or conquest. I'm not a huge fan of conquest simply because I like the idea of rush- having played CS since it was a beta. So I lean toward rush as the go-to game style I prefer playing. TDM I find horribly dumb because of the really stupid spawn points and seriously limited map sizes for what would seem should be much larger.
So when you join a rush server with the intent on playing well and helping the team and being a great squad member only to then watch half of the team you joined do dumb, stupid, and idiotic things that help no one on the team win the round, it really makes me
I could see where my similar viewpoint would call people COD sheep joining in on the BF3 front.... hence the reference to calling BF3 a 'COD' type game, when it is purely not.