It is important to clarify that Blizzard does not specifically identify users as smurfs. That is a very broad term that is perceived differently situation to situation. I do not use the term “smurfs” myself as it causes more confusion than it should. Here is what you need to know:
He also later responding to my question on whether we feel a player is boosting if they should be reported.
Finally, throwing regardless of the account being used should be reported under Gameplay Sabotage.