Matchmaking
Matchmaking is the process of organizing players in such a way as to encourage competitive and fun gameplay. The system uses a two-phase, score-based search method that takes into consideration several metrics. A score-based search method was used over other methods because it’s a good compromise between the often competing goals of match quality and short wait times.
At the start of matchmaking, the system attempts to find a match customized for the first Filter/Iteration/@rosters rosters (party) in the queue. If no match can be created, these players will be put at the end of the queue to ensure other players have a chance at a match customized for them. While this may seem unfair at first, this has actually been shown to decrease wait times for all players.
The first phase, called filtering, gathers players based on their current MMR and Ladder Points. The primary purpose of this phase is to both reduce the number of players being considered for a match, and to ensure that the match is appropriate given each player’s skill level. Over time, padding is added to your player rating and ladder points. While this may decrease match quality, it helps ensure that outliers still receive matches.
The second phase of the algorithm is the scoring phase. During this phase each player is scored against every other player being considered for matchmaking. The metrics used during this phase include: rating, rank, party size, profession, ladder position, and dishonor. With each metric the system is looking for players that are as close as possible to the average of those already selected. The system also attempts to keep the number of duplicate professions to a minimum.
Source: https://wiki.guildwars2.com/wiki/PvP_Matchmaking_Algorithm#Ratings
