SBMM or skill based matchmaking is used in multiplayer games like Call of Duty to match players based on a hidden skill rating to even the playing field for everyone. Sounds good, right? False. While SBMM is definitely great in competitive modes/games, it should never be used in casual matchmaking! Below average players might enjoy playing with/against players on their skill level at first but once they become better, the game punishes them for doing so by matching them with progressively better players. So the better you get, the harder the competition gets, the less fun you can have casually. Just imagine this: you played for multiple hours and had some great games with your friends before going to bed, next day after work you wanna relax and casually play some solo matches without having to go "full tryhard" but the game won't let you as you will encounter the same kind of enemies you played against last night when you were "in the zone" with your friends - there is no casual gaming anymore unless you get destroyed so the game matches you with slightly worse players for a few matches... the solution? Ranked = strong SBMM, Unranked = low/no SBMM! Don't force players to be competitive 24/7!