This mindset is self fulfilling. I've watched it grow over the years and am convinced of this. I have a 70% or so win rate on all of my toons, even those with 3500+ BGs played and 100s of thousands of hks.
Basically it goes like this
1. Join BG
2. Other team is russian
3. Heard about russian moaning constantly, convince yourself they're better than you, right from the start
4. Either don't try at all, or at least play thinking you're substantially worse than them
5. When you lose because you didn't try, this reaffirms your idea that "russians never lose"
6. Next bg you try even less
Another big part of this weird mindset is the assumption that all russian teams are premades. Listen, they removed the ability to make a Full premade i think in 3.0 or possibly even 2.0. You could bypass this filter by using an addon i think it was called AVhelper or something. This is how people did 40 man raids to farm honorable kills. This addon was broken in 5.0.
The reason russians only get queued with russians is the language barrier. Its that simple.
So right from the start, you're starting by assuming they are better than you, thus not trying, and they are more organised than you, thus you have no way to win at all.
And yes i have played against both horde and alliance russian players most days since legion (thanks to the mercenary mode)
As I write this I am 3 capping a russian team in Deepwind Gorge
http://eu.battle.net/wow/en/characte...atistic#21:153
^ warrior, main character, 67% winrate, 3500 bgs
http://eu.battle.net/wow/en/characte...atistic#21:153
^ latest character, ret pala, 72% 300 bgs
http://eu.battle.net/wow/en/characte...atistic#21:153
^ alt i play pretty regularly, 67% winrate, 2000 bgs
http://eu.battle.net/wow/en/characte...atistic#21:153
^ warlock i abandoned in wod, 65% winrate, 900 bgs
Other chars with under 300 bgs have 70-80% winrates, but i abandoned them in cataclysm.
Win rate is typically easy to keep above 50%, if you just focus on objectives every now and then.