Alright, so I'm new here, but I'm going to $#!+ on kenpom a little bit. Not saying his numbers are wrong, but let's look at the NBA, where there is some real coaching going on.
Graph 1 is relationship between 3 point D% this year and last year, for all NBA teams. There's a little bit of a slope, but not that much going on.
Graph 2 is only the teams in the NBA who have the same coach this year and last (and so are presumably running the same defensive system). Well: much stronger relationship. (R squared is .15)
[attachment deleted by admin]