Skill based matchmaking

So i just have some general questions regarding multiplayer. First question is how does the skill based matchmaking work? I feel like i cant play with my friends because if i play a while by myself with randoms the skill seems fair and i may not score top of leaderboard but i do well enough. However if i play with friends that are new to halo so they have a different skill level, it seems the next time i play alone with randoms i get absolutely demolished. I dont know how many games i lost in a row yesterday but it was rough. Each game felt like i was playing halo for the first time. It eventually regulated itself and i began feeling more on par with my competition but it felt like a good chunk of time losing. I dont mind losing mind you im just trying to figure out if playing with my friends whose skill level is lower is causing me to be moved up in matchmaking to higher skill games where i begin struggling in every engagement. If thats the case how can i play with my friends in a way that doesnt mive me so high up the matchmaking ladder because im not that good. Im an average player at best. Last question i have , does your rank affect casual play. Im ranked at Platinum 1 i dont play ranked often just when im in certain moods and i only play with randoms or other people around my rank. But in casual play i do play with anyone. Sorry for the long post i appreciate any advice or answers in advance

It’s complicated and not really possible to know without a 343 engineer actually explaining it. There are some papers on TrueSkill 2 if you’re really interested.

The TL;DR of it is you rank up by winning. Having a high impact on the game reduces the amount of points if you lose, and gets you a lot of point if you win assuming equal team skill levels. Nobody really knows if you’re ranked affects you casual skill level. Just based on my own experience… if it does not very much. The few times I play non-ranked my first few games are laughably one sided.

As for why you get demolished while playing alone. You probably are playing against people at your skill level and taking bad gunfights where you get punished for it. Play more carefully.