John Eberhart touched on this in a recent D&DH article. His theory (this is paraphased) was that the bucks in lightly pressured QDM areas grow up and would have encounters with hunters and realize they're not getting shot so their "I-gotta-get-the-hell-out-of-here" reaction time is slower.In other words, they tolerate something out of the ordinary moreso than highly pressured bucks do.