Ping Pong Rankings

Yes - Ping Pong Rankings - my new office space has a ping pong table and we are beginning to track the results to have a current ranking available. I am running the ranking based on score differential, but want to add in a modifier or weighting scale for increasing the reward for defeating a tougher (higher ranked) opponent and conversely decreasing the reward for defeating a lesser (lower ranked) opponent.

Really don't want to share what I have built so far because I don't want to persuade the design.

Let me know if you have a good starting point. Thanks!