there's really not that much guessing necessary. Google knows the click through rate of all SERPs, so after a year, if they see that 95% of your pages are never

there's really not that much guessing necessary. Google knows the click through rate of all SERPs, so after a year, if they see that 95% of your pages are never visited, they have no reason to hang on to them. Because those pages weren't bringing traffic anyways, your stats don't change