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In this tweet Benjamin Portheault gives this alternate scoring for the current Wijk event:

Shark point scoring

Can anybody explain what is going on here beyond just Sharkpoints = Waste + Points? What are they supposed to be measuring? Where do these numbers come from? If they are supposed to give a fuller (probably just different) view because just "points" isn't enough then they fail because "Sharkpoints" also fail to account for "waste".

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Benjamin Portheault links this tweet as an answer to a similar question under his tweet. If I understand the metric correctly, then each game is evaluated and for the worst and best positions of that game a win probability is computed. The waste points are then taking the win probabilities of the best evaluations and compare them with the actually achieved points. Similarly, the save points are computed for the win probabilities of the worst positions and compared against the actually achieved points. The shark points is then the number of points a player could have achieved for never "wasting" together with their actual "saving".

For example, Vincent Keymer appears to have played many games in which the engine was giving him good evaluations at some point in the game. However, he did not manage to capitalize on that and scored only 3.5 points. According to the waste measure, he should have scored another 4.51 points to a total of 8.01. Magnus Carlsen, conversely, was often in positions that were disfavored by the engine. Yet, he scored a total of 6 points, which is 4.06 points more than predicted according to the save measure.

As the all these measures are computed as the sum over probabilities, they do not correspond to actual game outcomes (as can be seen by the decimal values) and it could be that two players would gain shark points for the same game. For example, if Keymer plays Carlsen and first Keymer reaches a position that is strongly evaluated in his favor, and later Carlsen has the better evaluation, but in the end they draw. In this case, both players would have "wasted" this game and would have corresponding waste and shark points. Yet, realistically, only one player could have turned their advantage into an actual score point.

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  • Thank you. That was very useful. It also helps answer the question I really wanted to ask but couldn't because it is opinion based, - "Why should I care?" And what I get from what you said is that "Sharkpoints are useless (IMHO) but "waste" + "save" is interesting because it looks like a measure of reliability or steadiness of play. So, for instance Aronian has a "steadiness" index of 2.66 (0.81+1.85) (playing like an old pro) while Carlsen has 6.07 (playing like an erratic youngster).
    – Brian Towers
    Commented Jan 27, 2023 at 14:26

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