Something happened in other leagues too.
In C11, my Lima team won game 6 at home to win the LCS. Subsequently, today, I noted I had only 24 men on my active roster. Howry had been farmed out by the system (he still had remaining use).
I suspect your players were farmed out after the series, but unsure.
My C11 opponent in the World Series to come, Valencia, has only 19 players on the roster at this time.
Something happened.