So in week 1, the #3 team beats the #1 team at home by a touchdown. The #3 team then moves to #1 and the #1 team moves to #7.
So, if these were the actual rankings heading into week 1, then the #1 team would have beaten the #7 team at home by only a touchdown. The #1 team would have then fallen to #3 in the rankings and the #7 team would have climbed up to #4. Let that sink in.