You should tell people if you're not ranked ready

I find this to be the case with junglers often, but the rule applies to any position. If you get a role you don't usually play, you should tell your lobby. While I believe Riot should ID in the lobby anyone who gets filled, in lieu of their responsibility we should be telling each other "Hey, I got mid and I don't really play this position."

It gives everyone the option to either A. swap or B. accept their fate. For me, failure to announce often goes like this:

I get top, their jungle is all but camping my lane, our jungler seems both unaware of the situation, and when alerted, incapable of responding through either counter-ganks, or camping another lane and telling me to hug. Most often they say nothing which I take as an admission of their own failure, but it needs to be said earlier than 3 deaths in.

Whenever I check their match history post-game, I often find no jungle role assigned in the last 20 games.

Again, this is ranked. And I again blame Riot for not incentivizing Normals appropriately so that people have a reason to play Normals, but despite their shortcomings, the community needs to have some integrity and admit when they aren't great at something. If you do care about ranked and climbing, everything should be done to mitigate risk and increase the opportunity to win. That starts in the lobby, and admitting there's a role you're just not great at.