Rather than I explain it, here's a full rundown from the Sac-Joaquin Section on how each basketball team - boys and girls - receive their power rankings.
Basically, the top 16 teams from each division (except Divisions V, VI and VII) get into the playoffs. There can be more if, for example, a league champion earns a power rating lower than the top 16 in that division. There is usually a "play-in" game with seed #17 (the league champion) and #16 a couple days prior to the start of the bracket of 16.
There is also a "power ranking" assigned to each league in the Section which can go a long ways towards getting more teams in some leagues/conferences into the post-season. The Delta River League, in both boys and girls, has the highest ranking number (8.2) of all leagues. That basically is figured by how good all the teams in the league are each season.
Read more about this on the section website. I will add that next week the first of the team power rankings will come out. That will give us some idea on which teams have a chance of making the playoffs.
Most leagues will start their second go-round of conference games next week.