The system with regard to support specifically just doesn't work as intended at all. It's funny, it worked OK in the first few days because people were actually using "fill", but no longer - everyone learned their lesson. Here are the problems:
- The "Fill" role _IS _"Support". There is literally no difference between the two buttons. Both result in you getting Support.
- You cannot choose support (or fill) as your "second option". Doing so will result in you playing your first option 0% of the time. The last 50 games I played were all support because I want to play Jungle primarily and Support secondarily. That's what I want to do, and so that's what I select, and yet I play nothing but support.
SOLUTIONS
Solution: Force some weighted randomization between the roles chosen. So if I say I want Jungle | Support, then when I do, roll an RNG that's like 60% Jungle, 40% Support. Don't tell the player which one got chosen, but if it chose Jungle, now you just sit and wait until a Jungle spot opens. This is a pretty good solution in my opinion. Wait times go up a bit, but players have an experience similar to what they would expect from your system.
Bad solution: Own it. This would involve deleting "fill" as an option and making it so that if you make Support as a secondary or primary option, you can not select any other options. Basically this would be Riot essentially admitting that no one wants to play Support.
Solution: Provide IP rewards for playing roles that are less popular. This is also kind of bad because you're similarly acknowledging that you have roles that people don't want to play, but it might be a good stop-gap for the next thing.
Great, hard solution: Make support something people actually want to play. This would be a huge project, but I would say you can start by deleting all of this extra fanfare regarding getting kills. Delete the "multi kill" shit. When you have this giant banner that comes on the screen saying PENTAKILL, it sends a clear signal that the game is really all about getting kills. In fact, it is not about getting kills at all. The team with fewer kills can and sometimes does win. So by putting focus on kills - something support shouldn't be doing - you're basically telling your audience that support is a lame role to play.
I feel pretty confident that Riot will do something about this - it's pretty obviously not working properly - but looking forward to seeing what they specifically do.