@Riot could we get an explanation on how auto-fill works?

I just played a game where our jungler, a support main, had been auto-filled and our support, a jungle main, had been given I assume his secondary role, but he could've been auto-filled as well, didn't ask. How does that work out? Two players are not given their primary selected roles for what reason? I don't understand.

Auto-fill needs fixed or removed... at least at lower elos, silver-gold have plenty of players queuing up, improve matchmaking, remove autofill.

If it is kept, perhaps you could add primary role icons above your icons in champion select, so we can offer to trade roles in the small amount of time we're given.