What evidence do you have to support this claim? Did you go through every premier and non-premier tournament, calculating the variability of skill in each, and showed that premier tournaments had a smaller skill discrepancy? Or is this purely an assumption?
Let me introduce you to the law of law numbers:
https://en.wikipedia.org/wiki/Law_of_large_numbers
What this law states is that you canât define an average for a small sample. Think of it like this. What is the average of a single coin flip? Itâs either 100% heads or 100% tails. Does a sample of 1 define the rate of heads and tails? Nope! You have a bad sample that is too small to get a good average.
The same applies to premier tournaments and SC2. 15 is not enough to get a good average. You need at least 30, preferably more. Does this mean zerg is OP? No. Does this mean zerg is UP? No. Does this mean zerg is balanced? No. What this means is that the listed evidence is incapable of supporting any claim because the sample size is too small.
We can perform this experimentally. Here is a website that flips coins for you:
https://www.random.org/coins/?num=10&cur=60-usd.0025c-nj
Here is my first flip: 4 tails, 11 heads. 36%/63%.
Second flip: 7 tails, 8 heads. 46% / 54%.
Third flip: 9 tails, 6 heads. 60%/40%.
See? 15 is not large enough to give an accurate average. Now lets average all three sets, for a total of 45: 20 tails, 25 heads. 45%/55%. As you can see, even with a sample of 45 our result still varies by a difference of 10%. Thatâs why with a statistical test, you need a >90% confidence (or even better, >99%) because it minimizes the odds that you are wrong. To get a higher confidence, you need a sample even larger than 45.
15 is just too small of a sample to have any meaning. This evidence is insufficient to support your claims. You either need many more premier tournaments, or you need to include non-premier tournaments. The variability with small sample sizes is too large to be able to measure anything.