Thomas Shey
Legend
IME, Mutant: Year Zero and games based on that engine are more swingy than most dice pool systems because you only succeed on a 6 on a d6. This compresses the results a lot. To use Gorgon Zee's example with 8 dice vs 2, that gives you about a 27% chance of a tie and about 8% of a win for the 2 dice (barring rerolls). If you instead had successes on 5-6 (like Shadowrun), that would instead be 12% and 4%.
Oh, that explains a lot. Yeah, with that low a probability of success per die, you're going to need a very large number of dice before you have any stability. My experiences have all been with die pools that were between 30-50% chance of a success per die.