Speaking as a mathematician (cough), there does seem to be a season-to-season correlation between performance and attendance: the attendance increases from the previous season if the final league position is higher and decreases if the final league position is lower EXCEPT for 2005/6. As that does not follow the trend, I would ignore it
I wish I could draw a graph...
But in general, and I've said this before, fairweather Latics fans turn up for the "magic of the Cup" rather than high league positions. I wonder if this is something to do with instant gratification... As the Hudders cup match attendance showed, it is less to do with the "quality" of the opposition than previously thought.
Hope this helps!