How did you make the Runs Created stat equivalent to PB Value?

If both PB value and Runs Created are essentially normally distributed (I suspect they are close enough), and you used a constant (the ratio of mena PB value to mean RC) as a multiplier, once again when looking across a whole league you would, by definition, see the mean difference between the two to be 0, as you found.

Think of it this way - I could take player waist size in inches (which is probably normally distributed), put it on the PB Value scale, and after I calculated the difference for each player in the league (PB Value vs PB Waist Size), the sum would 0. Even though the actual correlation between the two would be very small.

I don't think the results you quoted from the method you used tells you anything about PB Value accuracy, sorry.

Fred Cline