I agree that the google SERPS depends on more than 100 factors. A model:
PR (for the model with 30% weight) and the rest (more than 100 other factors with 70% weight)
That means, that the other have in the middle 0,7 % influence of the SERPS (some more than 1 %, the rest less than 1 %).
But that means also, that the influence of Pagerank ist very, very big, but the influence of
all other factors together is bigger.
Therefore we see sometimes in the SERPS somethink like this:
position 1: page with PR 4
position 3: page with PR 6
