I personally think that there are a lot of algorithms at play in almost everything concerning RNG and DF. For instance, there was most certainly something up with World of Darkness. We noticed that it would *only* drop DRG gear for the longest time, but it seemed to change based not so much on our party composition, but our party history, since we ran with a static. Similarly, the game liked to queue myself and my tank up with brand-new players when farming for tomes early on when we were playing our primary jobs. When we weren't, however, it tended to give us veteran players. I hope I'm remembering that correctly, but we most certainly noted that there were patterns when it came to the randomness of the game.
In the case of Seize, I noticed that I tend to get the same players pretty frequently, no matter what time of day it is. Surely there are more than 40 or so Malestrom players going in, but I think it tries to match people not based on rank, but perhaps how often they play. I've ended up in parties that had just played a round together without partying up beforehand, and knew none of them. Yet when I requeued later on, I ended up with the familiar faces again.
But I digress. On another note, how often does the community receive any acknowledgement from moderators or the development team concerning PvP? They seem pretty active in other areas, which is great, but it seems that this is abysmally low on their priorities list.