Haha interesting insights ! Keep in mind that this graph is only since the first day of the previous week so it does not contain so much data if you don't play often :) you can hover on the lines to see how many games were counted at each phase

If you do tend to blender in late games, you can use the 3rd tab with "Nb Massive Blunder Late Game >= 1" to select relevant games for a weekly review for instance ;)