the ratio of per to lp is somehow involved in determination of type of shot attempted. This was clear immediately after the new engine when low lp guards were jacking wayyy to many threes. There is a minimum value in there somehow now. I rarely use positive values for 3 pt setting, and only if the PER is particularly high, but I am a bit conservative. I do think that if you set to negative you will increase attempts in the paint, while positive will increase 3s in general though, so going negative with poor lp I think is risky, but I don't know for certain...