Can anyone explain explain the following:

Before an away series I try to calculate the PAUse and Use ratings for players close to their usage maximums. I use these values to figure out whether the payer is likely to becomr Overused during the series. In a recent series I see something that doesn't square: A hitter (Nilsson) is rated OverUsed with a PAUse of 124. Now, according to my calculaitons, after 105 games the PAUse value at which a hitter becomes Overused should be 128. This comes from interpolating the allowed usage values from 150 at Game 33 (i.e., first game after the first 20% of the 160 game season down to 110 at Game 160.

Does anyone know where this calculation is wrong?

Also, I think it would be useful if PB would publish the OverUse values before each series.