Amen, Pav. You have to look at those rankings in the context of other questions: how competitive is the time period; how is the lead-in doing; is the show scheduled on a night with high or low viewership; is the show on a lower-rated network; has the show improved on whatever was previously airing in that time period; are the show's ratings trending upward or downward; is the show expensive to produce; does the network's parent company have financial interest in syndication; is this a new show with a lot of creative potential or a played-out show on its last legs.
I see these posts talking about season rankings again and again, but the execs running the TV networks look at many, many other factors when deciding to cancel or renew.