Love the new forums but still could use some major improvements...
Thoughts on Conversation Flow:
I think the key here would be to come up with a way to allow splintering in a way that doesn't disrupt the normal discussion flow while also cutting off posts that add nothing of value whatsoever to the discussion. Example -
Subject: Let's Talk about Ahri
Post 6: "fkn riotoesn't have a clue how to balance this gaem"
Post 42: "I know this is not directly related to Ahri but there was a Huemerdinger rework that was announced months ago and we haven't heard any word on it since. I was wondering..." (with well-articulated thoughts, questions, suggestions)
Post 6 should be hidden by default (potentially deleted entirely should it's rating become low enough?). Post 42 is not directly related to the OP but it's a valid line of discussion that other players and maybe even a Rioter might want to respond to. The thing is, I might not care about Huemerdinger and I don't feel like seeing the post about him or any of it's replies. Maybe someone else IS interested and they want to follow that line of discussion. There should be a way where trusted members of the community or Riot can redirect replies to new threads when appropriate. When such replies are redirected their content no longer appears in the "parent" thread and it is replaced with some sort of indicator showing that the reply was redirected along with the new subject of conversation.
The problem here is really "How do you deal with threadception?" (and the problem with that is "How do you determine what threadception is valid?"). Determining what is valid and what isn't can only be accomplished by the hive mind of the community because of the shear manpower requirements. Dealing with threadception itself is "easier" in that it requires intelligent UX/UI design.
Thoughts on Finding Content
Tags. Think: StackOverflow. I don't believe that anyone should be able to come up with whatever tag they fancy (it's great in theory, horrible in practice because you end up with: leagueoflegends, league_of_legends, league-of-legends, etc etc) because over time the tag pool becomes so polluted that it might as well not exist. However, standardized tags are absolutely fantastic for narrowing content down as you can rely on them to give you all of the results that you were looking for (provided the results were tagged appropriately). The community should probably be able to suggest new tags somehow but definitely not create them directly.
It would also be create if "trusted" community members could edit the tags/content of posts to make them more readable and relevant. Obviously this could lead to issues trolling and whatnot so trusted has to mean something other than simply "Have X amount of posts and Y amount of rating points." If implemented correctly the forums would be a -much- more enjoyable place to browse and post in.