AbigailII: Such a single datum isn't really an improvement over an average. Consider our chess player with a 30-days chess game but who loves a quick game of backgammon.

I do think a time per match metric is better than a time per move one. Those 5 anti-backgammons with the friend would only be 5 matches rather than 500 moves and would therefore distort the average much less.

All: One think I'm not clear on, where is the information to be displayed and how and when is it to be used?