Preseason rankings are always the same as final rankings for the previous year, with one exception. If a team did not compete last year, that team starts at 0.00. Normally this works well, except for this year. Ankeny won the class 4A title last year and is now effectively two teams: Ankeny and Ankeny Centennial. So the default behavior is to set Ankeny to this 2012 strength and Ankeny Centennial to 0.00.
In week 1, Ankeny Centennial beat Ankeny 17-7. In the week 1 rankings, the computer dropped Ankeny to about 47th and keep Ankeny Centennial about 48th. Clearly this does not seem reasonable.
For now, I set the preseason rankings of Ankeny and Ankeny Centennial to be the average of the best team and worst team in 2012 4A.
In the off season, I will test further: what is the correct assumption of strength for a team that splits in two and both resulting teams remain in the same class. A similar event happened when Highland-Lone Tree split (at one time in the past), but then both teams competed in a lower class.