Often I would like to have an estimate of a player’s true talent in a past year. Projection systems are always only focused on predicting future performance based on past results, but what I wanted was the best estimate of the expected performance for a player in a given year, based on his results in that year and the surrounding years.

I wanted to find suitable weights to assign to performance in the given year, plus the years immediately before and after, and have the right amount of regression to the mean. But I kept running into the same mental block; how to assign a weight to the given year’s performance, since that is exactly what I am trying to “predict”?

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