Unranked to Diamond in 7 hours

[zeth07]

That just sounds like random luck to me. I doubt they're deliberately engineering teams to that extent.

Sounds like confirmation bias to me. The last character i ranked to Crystal rode a win streak straight through Plat without interruption.
Folks have been complaining about the matchmaker artificially forcing losses on them to curb their win rate for as long as PvP games have had matchmakers.

I understand the frustration with getting CC locked, but the alternative would be cutting way back on job mobility and survivability, and I think that would be much worse.
Attrition models for PvP tend to be boring as hell, and aren't really suited to this high octane short round format.

I'm not saying FFXIV devs would care enough to set up some elaborate matchmaking for their PvP, but there have been studies done on matchmaking and I'm sure some game devs out there have implemented those exact kind of systems where random isn't true random in regards to matchmaking meaning it is potentially rigged under specific circumstances.

See the EOMM study.

This is entirely possible because they implemented a Streak Bonus mechanic. So they could see that a player is streaking and purposefully try and throw them into a harder match.

Even speaking from my own experience I felt like I had the exact situation happen to me. I won 5 straight matches getting to Silver 1 and on my promotion match into Gold they put me against Gold+Platinum players, opponents and teammates, even though I was still Silver technically.

I ended up losing, and from that ended up losing my next 5 out of 6 matches. The whole time leading up to that I've never seen Platinum players during Silver, because it should be Bronze - Silver - Gold.

One of the examples in the study showed that people who Lose 3 straight matches are more likely to quit. So in that same regard if you hit a losing streak they should in theory try and give you an easier chance to win.

Again I don't know if FFXIV devs wanted to put that much effort into matchmaking but it's not impossible that there are other factors being accounted for.

Reference:
http://web.cs.ucla.edu/~yzsun/papers/WWW17Chen_EOMM