While I do think you have a reasonable point, I still have to approach you position with some skepticism. Here's why. Shrewsbury was on Matt's staff for several years, and he is known for crafting NBA level defenses. You would think that "Zone" would have crossed into the vocabulary at some point during his stay at West Laffy, right?
Did we see PSU use zone when Shrews was there? I don't think we did, so maybe there is a solid reason behind Painter's approach besides the false "He is too stubborn" argument? At this point, I am well outside my level of knowledge about the sport, so I am just running on "loose change" right now