As you can see from the topic, there are two competing concerns with the ranking system. There are those like Scavenger’s, people who are concerned with bad players unfairly earning a higher rank than they deserve by abusing the matchmaking system (though I think this is more frustrating in Halo Reach because of the percentile placements, someone abusing the matchmaking system by “iron boosting”, i.e. playing with someone that has intentionally deleveled their account to help his friends rank up faster since the game thinks they are carrying an iron teammate, so someone who iron boosts gets an Arena placement is actually taking someone else’s placement. For instance, I don’t think it’s fair at all that someone that earned a Top 1% Onyx by winning 145/150 games against single-digit Onyx players, but someone playing with an iron booster can get there by winning ten games against single digit players (and they aren’t punished for a loss at all either, since the game expects their team to lose) and that iron-boosting player can take the 1% Onyx rank away from someone that earned it legitimately.
In this regard, I completely agree with treating low-level accounts as the level at the lower-end of the skill range with which that player can match, as the OP stated. If a level 1 player is searching with a level 50 player, he should be treated as a level 40 for the purpose of calculating the change in TrueSkill of both that level 50 player and the opponent’s ranks (though the level 1 should rank up as fast as he normally would by beating level 40’s, since he clearly wouldn’t belong in those low levels if he’s able to consistently win). I mean really, someone that is a high-level is probably concerned with his rank, and thus he wouldn’t ever search with someone that is level 1 (or a single-digit Onyx player wouldn’t ever search with a true Iron division player, etc).
The only possible abuse of this proposed system that I could foresee would be “circle boosting”, since one could easily shove a new/Silver/etc account on a level 50 team and rotate who they win/lose to (as it would be treated as a high level, and thus saving circle boosters the time of leveling up their throwaway account). However, I trust there would be a system in place available to discourage circle boosting as I’m sure there already is (can’t increase TrueSkill after matching the same people more than X number of times, flag matches where the same people as matching each other repeatedly to check for suspicious activity, etc).
Then there are the concerns of the casual player, like Methew’s. Sorry buddy, but as someone who broke out of the so called “rank lock,” I don’t exactly sympathize with you. Players don’t magically get dramatically better overnight, and there’s no reason the game should expect someone that loses a bunch of games at level 40 to suddenly rocket through the ranks of 41, 42, 43, … etc overnight just because they won a couple game in a row. Compare this event to random chance-- if you had an exactly 50% chance of winning (because in this hypothetical scenario, every player is exactly the TrueSkill they deserve and the teams are evenly matched), it’s not that improbable to flip a coin and get heads 4, 5, 6 etc times in a row. Try it. Flip a coin 100 times and record the results. Even though the odds are 50-50, strings of heads (or tails) are not that unlikely to occur at all. But in Halo, players that are “rank locked” have likely played 1000+ games, and you can try flipping a coin a thousand times (I’d recommend a computer program to simulate this) and see that it’s entirely possible you could reel off ten straight heads at some point. To rank up with the TrueSkill system, the system needs to be convinced that the outcomes of the games are not due to random chance-- that is, that a player is consistently beating similarly skilled players because one of the assumptions (i.e. that player’s TrueSkill level) is incorrect. The way to do this is by consistently beating higher-ranked players. Odds are that if you consider yourself “rank-locked”, you are not doing this. I also implore you not to use terms like “your sigma got you rank locked” when it is clear that you do not fully understand the basic statistical principles behind the system. Further, no, your TrueSkill does not jump wildly from game to game, and in reality, your “TrueSkill” is actually a range of levels. In Halo 3, the lower bound of that range was the rank displayed to you.
HOWEVER, with that being said, I DO support the idea of JoinTheFlood318 (although with a number much greater than 50). That is because I do believe there are people in Halo 3 that have like 10,000+ games and are level 49 (a Brigadier Grade 87 or whatever). I do believe there is a point where a player might truly be a level 50, but that it is infeasible for them to win the required number of games to rank up to a 50. Even if you operate under the assumption that this person is the single greatest player to ever play the game and so are his teammates, it’s nigh impossible to win 100-200 straight games because of extrinsic factors. For instance, when I was searching alone in Team Slayer not too recently, I was cheated (DDoSed, hostbooted, whatever) seemingly once every 4 or 5 games. Regardless of how good of a player I am, there is no way to beat (competent) cheaters without somehow cheating yourself.
Now again, looking at potential abuses of this system: I believe considering your X most recent games could be hazardous because it could easily be abused by the boosters mentioned in part 1. For instance, if only your 50 most recent games are considered, me and my Doubles partner could take turns losing 50 straight games (deleveling, quitting out, etc), have the game consider us to be really bad players, and then play with my doubles partner and very effectively boost him. Then we swap, he delevels a bunch, boosts me up, and now both of us have “highest skill 50.” I don’t think there should be any game mechanic that encourages more quitting, deleveling, etc, as that person would then be ruining the experience of 7 other people in 50+ games each time. So again, such a system would have to be cautiously implemented to prevent such abuse.