There have been 180 tournaments in 2019. Zergs have won 57. Thats 32%. Serral alone makes up 12% of those wins. Without him the wins drop to 28%. Assuming the base rates of zerg are 33%, it means zergs have a 16% reduction in tournament winning performance which is strikingly similar to the data in this thread.
When your beliefs contradict the facts, it is time to revise your beliefs.