I have come to the conclusion, as Bob Jewett suggests, that the best way to handicap players is by their wins/losses, and also their wins/losses against players of equal level or above.
I have started to compile such records and it is actually very eye-opening and telling. It sure beats using just the average. There are many players that don't have high averages but it is extremely difficult to beat them. They may average .600 but their defensive play is so strong that you end up always averaging only .500 or .550 against them. Of course I am not referring to our top players who can break safeties better than the rest of us.