From what I've seen watching ECS is that it does stack above 4. As an actual example tooday in the Mouz vs Vitality game. Vitality wins the first 4, Mouz gets to 3400. Mouz wins round 5. They then lose 3 more in a row. Then win 3 in a row. Now if it didn't stack above 4 they would have gone down to 1900 instead they get 2400.