I may be a couple years late in addressing some of these problems, as most of what this post is about is from the "skill-based matchmaking" implemented in 5.9.2. However, it's the mixture of that with some of the newer addenda to PvP that is making for some real problems.
First off, anecdotally, I'm not convinced the matchmaking system is coming anywhere close to fulfilling its stated goal. I started PvPing in 4.0.3. From that point until 5.9.2, it seemed like close, hard-fought matches were the norm and ROFLStomps were anomalies. There were brief times when that maybe was less true, like right after the server merges, but that was the overarching trend. For the past two years, that's basically been flipped, where one-sided matches are a frequent occurrence and close fights stand out. So strike one for this update not even doing what it was advertised to do.
Next point is what this post is titled for. Ever since 5.9.2, it seems as though the pool of players that you can possibly get teamed up with or pitted against has drastically shrunk. Now this would make sense if people are grouped based on a skill bracket, but what even goes into determining said skill bracket? Why are decided number-farmers in the same bracket as players who focus almost solely on objectives, and why is either in the same skill bracket as people who AFK whole matches and only do anything to avoid being vote-kicked? Winning or losing, IMHO, it gets stale to play with and/or against the same players in nearly every PvP match that I go into. Variety is the spice of life. You know what everyone's play style is if you've been PvPing for any length of time, and while pvp matches are rarely 100% predictable, the fewer options of who you can play with and against certainly makes it more so than it was before the range of opponents/teammates was limited by 5.9.2
Conversely, as a consequence of this, it's next to impossible to avoid queuing into certain players. There was a time in this game where you could wait a few minutes and leave a rotation if you didn't want to play with or against a certain team. Not anymore. Don't wan't to play with that zerg team again? Too bad. Now, if you wait a few minutes to queue again in hopes of getting out of an unfavorable or boring rotation, you'll actually end up waiting 10-15 minutes for the next most ball-busting or repetitive team comp the game can find based on this narrowly-defined tier it's shoehorned you into. That's ridiculous. As others have emphasized on this forum in different contexts, this is REGS, not RANKED. Queue-dodging doesn't merit any consequences.
Related to the previous point, because the game formulates regs matches based on these very specific skill brackets, pop times have been on average much slower since 5.9.2 than they were before it. On its own, this is already not a good thing. People who only have so much time to game aren't able to get in one last match they wanted to play because it took an eternity to pop. Mix that in with the LEGACY-WIDE Deserter lockout and loser-gets-nothing mission rewards (Either one of these things without the other would be justifiable, together they're ridiculous) and you have some not good stuff. Mind you, plenty of people get booted from matches because of shoddy ISP's. I know the game has no real way to distinguish a genuine disconnect from a ragequit, but this is a little draconian. I'm sure at least several of you reading this have at least one night of PvP in a week where you're stuck on the same losing team match after match, you make zero progress on your weekly, your pop times aren't even that quick, and of course, you can't quit the match lest you be locked out so your only choice is to sit there and take the beating.
Something has to give. Whether it's the drastically-reduced variety of other players an individual PvPer will get to see on a weekly, nightly basis, the loser-gets-skunked mission rewards, the slow pop times, or the legacy-wide "F*** you" for leaving a match, the current landscape is making a staple of this game a test of patience for many players.