Team Builder was a queue introduced on League before the introduction of the new draft pick. Within Team Builder, instead of queueing for a role or queueing for nothing whatsoever, you would queue as a specific role and champion. For the leaders of the groups (those that made their own lobbies instead of queueing for another person’s lobby) there also was the option of choosing which roles you wanted on your team, and whether or not you wanted to accept someone that showed up in your lobby. This also means you could queue as five mid, if you had the patience and could find the people who were up for doing the same.
The addition of the Team Builder queue (similarly to the new draft pick modes) was aimed at making the player experience better (as you could secure a role you’re good at playing, there would generally be a more positive atmosphere as no one was stuck with something they did not want) as well as it was likely to increase the game quality for having people play their primary roles a lot more often than when paired randomly with people in a queue.
One of the things Team Builder (and the development of it into the new draft pick) was aimed at fixing is misconceptions about player intent. In old ranked games, where no roles were assigned, most fights would start about positions in game. This would sometimes quickly escalate and end up with a negative experience at the start already. Most of these players however shared the same common goal - winning the game. This means that the root cause of the main type of conflict with old draft queues would be solved with the introduction of Team Builder and its successor. (Of course this doesn’t do much against players that intentionally want to throw games, however this isn’t as much affected by the type of queue as it is just the player wanting to ruin other player’s experiences .
Another addition of the Team Builder queue that was aimed at increasing player experience was an individual ready check. Before queueing, every single player had to press ready before the leader of the lobby could actually queue. This was so that every player “agreed” with the team comp and people they were playing with, and as such tried to work on team spirit more, where there was a more positive atmosphere and less leavers .
Making the player experience better is something that most definitely ended up being the case: the “classic” Team Builder queue lowered reports by about 26%, increased honors by about 18%, reduced the amount of negative and/or toxic chat by about 36% in wins and about 23% in losses, as well as reducing the amount of AFK’s by about 8 to 10% .