This stat is really helpful for player profiling. In the current Player profiles you can set a range for vpip and pfr, but not a range for the gap between the two which can make it difficult to be accurate.
For example, if i want to profile fish as 28 to 40 vpip, with at least a gap of 15 in the current options I put VPIP 28 to 40 and PFR 0 to 25. But this would include a player who is 28/25 and clearly a reg not a fish.
Edit: There is a ‘Add New Stat’ button on the Player Profile screen but it doesn’t seem to be functional.