In the LFR, right now, let's say you queue by yourself.
You get into the group and there's 8 people from the same guild. Typically all 8 of those people will roll NEED on something that they somebody in their group would benefit from. Let's say a caster DPS trinket drops, out of those 8 people 4 can roll need on it, 1 of them actually needs it/is an upgrade, and you need it as well. So now that person has himself and 3 other people rolling for it, his chances of winning of drastically increased.
In the new LFR, the jist of it is, is that you won't see who won what items. RNG will determine what item will drop and who wins it. There won't be a Need/Greed/DE roll like there is right now. The items get handed out automatically. You'll also only possibly receive items that are appropriate for your roll. So if you queue as a tank you can't win DPS items.