Kor's guide to PvP Matchmaking manipulation:
The below applies primarily to Solo play.
So here you are, a good player. You've found yourself with a pretty good amount of Best around and Bright side medals, yet for some reason lately you've been getting more and more Bright Side medals and less actual victories. In fact, somehow, most of the victories you've gotten are when you are playing terrible and you end up in the bottom half of the scoreboard on your team. So why does this keep happening?
First lets talk about matchmaking. Bungie has a pretty good default matchmaking system. I would even argue that most matches that have no drop-outs end up being very close matches. This system, as it stands, works well. The problem actually comes about shortly after a game starts.
So the game has started, the initial wave is over and you find yourself kicking ass. The score is already 850v120 in your favor, you even have half a super bar already. And then it happens, your game is about to go to shit and you don't even realize it yet.
xXxRandom_EnemyxXx has left the game
Hey, no big deal right? That just gives you an advantage of a 6v5 in your favor, and right around the time of heavy ammo? Sweet deal. Then Heavy pops. You really have the advantage now. You got one heavy crate and neutralized the second. You've got a little over a 2K lead, and then you see it again:
iTzGuy_on_Other_Team has left the game
Pro_Snipez_Opponent has left the game
Wow, a 6v3? Well, the advantage is there, except now it's become so hard to find somebody that the game has slowed down. You aren't really gaining a bigger lead because of it as well. Now comes the turning point of the game:
U_gunna_get_wrecked has joined enemy team
1HKO_sniper_guy has joined the enemy team
Crazy_Aggresive_Shotgun_guy has joined the enemy team
Around now your team score probably looked something like this:
1800 - You
600 - Teammate 1
545 - Teammate 2
300 - Teammate 3
165 - Teammate 4
100 - Teammate 5
You, being a pretty good player, have been cleaning house this whole game. Bungie noticed, as did their matchmaking formula. In fact, it noticed so well, that it found 3 people on your level to match you against in an effort to get an even match. Sure you can square off against 1 of them, maybe even 2 of them. But your teammates? Those poor bastards are about to get violated more than a hot chick crowd surfing during Mardi Gras.
As the game progresses, you'll find that you've lost that lead, but you hope that you can maintain an even game. Except around 7500v7500 they break away. The enemy team starts using supers and all collectively picked up heavy while your team runs right past it. You end the game around 8700v10000, all because you played too well in the beginning.
So what can you take away from this?
It's actually pretty simple. You want to be the slacker on the losing team here. Believe it or not, the best thing you can do is play like shit the first 1/3rd of the game. Basically until the first heavy pops. If done correctly, you're more lackluster teammates will abandon ship and be replaced by competent players. Then you can actually play to your normal skills and reclaim the advantage.
So what makes me think this works?
I'll be honest, I've done some testing, but not enough to claim this as a sure fire method yet. Yesterday alone I played 17 games of Clash. Of those 17 I was on the winning team twice. Both times I was on the lower half of the score board. Of the 15 times I lost, I received 14 "Bright Side medals"
This morning I played three games and "threw" the match for the first 2 minutes. I won all 3 because my teammates jumped ship and I got some good replacements.
Final Notes
There seems to be several problems that need attention here:
-Players should have some sort of repercussions when abandoning a game
-Matchmaking needs to fill empty slots with players on equal levels of the entire team and not the better/best player
-Some sort of visible rank could help mitigate some of these situations.
And that pretty much concludes my theory. I will continue to test said theory for some time. As a final note, all my experiments took place in Clash. I'm not sure if other game types would work the same way.
I think matchmaking is just 100% completely random. Other than I think they try to match you with people who are physically close to your location. I don't believe there is any ranking going on at all, other than that for some reason they try to match you with Guardians of a similar light level but no PvP skill check at all.