looks dang good to me, bigfish!
i didn't mash the blueberries, but the raspberries, being frozen and then thawed, were pretty well mashed - i am sure that this helped hold the filling together.
Ii might be worth it to mash a few of the blueberries, but my guess is that you shouldn't need to mash too many ~
give it another try, and see how it goes - heck, pie is always in season!