Cary,
Here is a a simple idea. Remove factors like this from the Core Ranking system (or any ranking system you are looking at). Just do it (remove it) is my simple recommendation:
I know some will say that factors like this may belong in there because of “favorable interactions.” But I actually agree that some of the explanations on the P123 forum site are overly complex as well as not always being right. Removing factors like this is easy and best policy, IMHO.
Fitting to past interactions can lead to overfitting if you do want a more complex explanation. Past interactions may or may not persist. Find your own factors to remove but this is SalesGr%PYQ.
Even a little more complex to be accurate, this would clearly fit the definition of a noise factor partially responsible for overfitting. But it is even worse in that we fit to factors that are noise as well as noise interactions that may have helped in the backtest but simply do not work going forward.
There may be some advanced users that can articulate the interaction they were looking for in advance, and perhaps they may want to keep a few factors like this. It is great that they can do that. I am not that advanced myself.
TL;DR: remove the garbage that wasn’t even doing that well in the past with uncertain interactions with other factors in a future market. A future market that we know will be different with certainty.
FWIW.
Jim