You don't want to just average the performance across all leagues to determine the accuracy of the SIM. That is a pretty meaningless way to judge whether the SIM is working.

What is important is the performance stats in EACH individual league. The 10-20 replications you get from looking at stats across all TRAD leagues need to be looked at as separate reps.

Then look at the range of performance over the reps and the deviations from the average to determine if the SIM is working.

In other words, a player who had a .300 BA with 30 HR may average exactly .300 with 30 HR over 10 leagues, but if his BA ranged from .100 to .700 and his HR from 2 to 60; the SIM isn't working even if he averaged exactly .300 and 30 HR.

On the other hand if most of his peformances were within 20% of .300 and 20% of 30 HR but he averaged .290 and 33 HR, this was a much better SIM.