Seems you're on the right track, but I wouldn't pay too close attention to the PA and instead focus on culling the pages that offer no value to the user. The pages that are perhaps duplicate content, or can be merged with another page to create a stronger, more relevant page. Reducing or pruning the number of thin pages to maximise the value and quality of the pages you keep will help with the overall health of your website.
If you only look at PA, then you may end up getting rid of a potentially valuable page that simply didn't have the opportunity to perform well before.