According to Facebook, “News Feed will begin to look at both the probability that you would want to see the story at the top of your feed and the probability that you will like, comment on, click or share a story.” Basically it sounds like Facebook just wants to put stories at the top of your feed that it thinks you will most likely engage in.
After all, sometimes there are posts that we have no interest in but show up on our feed anyway because it’s coming from a source we follow. Facebook also notes that for Page owners, this might have an affect. For some Pages, this could mean an increase in referral traffic, while for some pages, they might see a decrease.
However Facebook hopes that ultimately this will rebalance what people are seeing in their feeds, so if you agree that your feed could do with a bit more tidying up, then this update will be worth looking forward to.