The ranking in the front page is affected by flagging. Usually, the more points a post has and the more recent it is, the higher it is ranked. But flagging pushes it down. So if you see a 100 point post submitted 10 hours ago above a 150 point post submitted 6 hours ago, it means that the 150 point post got flagged a lot.

Posts with much less points are shown higher up in the page than this post. That is usually an indication of the post being flagged.

See this thread for more details

https://news.ycombinator.com/item?id=5716010