A coach at the community college once told me that the biggest stat he looked at was rebounding, because if his team could out-rebound the opponents by 10 percent over the course of a season the wins and losses generally took care of themselves. So, based off that premise, a number of years ago I crafted the following formula, which I generally still use (with tweaks based on tendencies) designed to get me
Start with a base position of -2 for press, -1 for zone and 0 for man.
Adjusting team ratings for walk-ons, ineligibles and redshirts, subtract your opponent's rebounding rating from your own. Take that figure, negative or positive, and add it to your opponent's team PER rating. Using that new PER number, subtract the opponent's LP from it. If the number is -3 to +3 inclusive, play the base defense above barring some reason to adjust. For each block of five points in either direction, adjust the base positioning up or down accordingly, so a -11, for instance, would adjust the base down 2. A +18 would move it up 3, etc.
Like I said, I will call an audible every now and then based on tendencies, athleticism differentials between the teams, if I get adjusted into the +/- 4's and 5's because I usually prefer being adjusted into them rather than playing them from opening tap, or I see something on my opponent's roster that I fear worse than potentially losing the rebounding battle for that game.
Certainly not claiming its a perfect formula, but it has served me well over the years and even when down at the half I rarely get auto-adjusted off the number, which I have taken as a positive sign.