Originally Posted by
nsacpi
I don't know what "unique variance" might be, but I think different classes of players have different variances. Young pitchers, old hitters, etc. So there is more uncertainty for certain types of players. I think that is widely accepted. By the way, the players with the most uncertainty about performance are not necessarily the ones with the biggest risk. The biggest risks tend to be the ones with big long-term salaries.
The numbers given by Steamer and other projection systems is the expected value of the various possible outcomes.