Yes some of it might simply be from when people queue ranked on accident, but there is probably also a portion of them who go into ranked with correct specs and then end up lossing.
But because of the way they loose, they just dont come back. Because it seems rather hopeless.
I've said my piece previously what i think of BW in ranked, there are simply too many layers you need to win in the matchmaking for even getting close to a 50% winrate, just based on matchmaking of classes not only on the enemy team, but also on your own team! There are some exelent Singletarget rr80+ BWs on the leaderboard who are like 0-4 and didnt touch the gamemode again, because of the layers of RNG in the matchmaking and the way you can get shutdown and its out of your own hands. Unless you cheese the system and queue when you know who you will face on the enemy team/own team.

Also there is some decent data for how 4 RDPS classes are bottom on one of those statistics, and 3 of them are int users. Could it be that we have been able to softcap int since Conq era and have no aternative build paths apart from int+crit. And endgame with more statpoints available from city sets have just made phyicaldmg dealers the meta. Kinda predictable just following the Live trends and issues.
This server has pretty much always been majority casual nostalgia from the overall playerbase, releasing ranked after 90% of the 6mans had already left seemed odd.
Releasing Season2 of ranked when WoW Classic TBC with their Arena released at the same time, is just.... mindblowing.
The original Warhammer online was not balanced, and I honestly dont think it was meant to be. Two realms having different methods and tools of winning was the madness.
Trying to make this some wierd E-sports arena unmirrored unballanced gamemode is quite litterally splitting the gamepopulation in two camps, but only time can tell if this damage done can be corrected if the vision of the server gets put back on track. Hope ranked experiment was an eye opening reality check.