The losing team will start to abandon the match after the first loss or if they notice their opposition is good at PvP.
You get comms for losing, you just don't get daily/weekly credit.
If we are trying to maximize comms per hour
then whether or not leaving maximizes this depends on
- how long to load out of the current arena
- time for queue to pop
- time to load in to next wz+ wait to start
- probability of winning next arena
- probability of winning the current arena (miracles could happen -- e.g. the other side has 2 DCs)
- comms earned for a losing wz
- average time to finish a wz
- time saved by leaving wz
(caveat: by "wz" I mean ranked arena).
If we queue 4-man and have some buddies of equal skill queuing 4-man then we can greatly increase #4 by leaving a loser against a clearly stronger team (not our buddies) and requeuing. This does not require win trading per se as long as our buddies will keep queuing until we beat them them fair and square.
- we still have hidden ratings in preseason that are used for matchmaking (i.e. BW doesn't have separate rating/matchmaking code for pre-season and season).
- people who leave are only queuing for comms to earn gear. Presumably this is less common after pre-season
depending on the variables, it may be the case that staying gives the best ROI. Clearly the longer it takes you to load out, load in and get a queue pop the better staying and losing looks.