FYI there are ways to prevent being autofilled
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Be a man and eat the bullet. By playing ONE game as support you'll get AUTOFILL PROTECTION for next 4 games. Having guaranteed main role for 4 game is nice, isn't it? This is very helpful for players capable of playing support but terrible at ADC or JG.
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Be a smartass and abuse the system. You need to find a friend who is willing to play support for one game. Team up with him, pick MAIN SUPPORT and SECONDARY MID. He should pick whatever you want to play. There's no way you're getting mid over support, so just swap your roles in champion select. Enjoy your 4 game autofill protection. This way you always play your main role, and everyone is happy and satisfied. Repeat every fifth game for permanent protection.