Only 4 vehicles can be the top BR in a game on each team, giving you a 25% chance to get downtier. That means 75% of your games will be an uptier of some sort, being a +.3, .7, or 1.0. This is BEFORE battle rating popularity kicks in, like 9.3 getting solid constant uptiers because there are so many players at 10.0 and 10.3.
Typically this happens when the bracket 1 BR above is saturated with players. For example. Trying to play 9.3/9.7 air will pretty much always see you uptiered to 10.3 because of the sheer amount of 10.3 Premiums that exist. Inversly. you have a reasonably good chance to see a downtier at 11.7 because of the amount of 11.3 premiums being used.
Now they really need do need to add some kind of limit on how many uptiers you can see in a row. But i doubt that will ever be added
I have heard that it has something to do with player level. That high level means you are more likely to get uptiered.
But honestly. I have no idea. Sods-law I think. I get uptiered constantly at 9.3. So I play 10.3 and get constantly uptiered to 11.3.
The Gaijin MM needs a ground up overhaul. A big part to why I stopped playing ARB and started playing ASB. 0 Chance of an uptier that I didnt choose before hitting play
To be frank, the gameplay of full uptier and full downtier is a different ball game, I would call full uptier a difficulty tweak
Example: your 9.3 vs enemy 9.3s, 9.0s, 8.7s and 8.3s is a walk in the park for experienced players, where your 9.3 vs other 9.3s, 9.7s, 10.0s and 10.3s will give you less room for error, I can make an example for something like T-64s/T-72s in this different matchmaking, their armor is night and day difference.
During the sales of TURM 3 and VIDAR I have had a lot of full downtiers matches (150sp initial spawn point), you can see my T-72s are just bullies
Those 8.7 premiums make 7.7 and 8.0 almost constant up tiers, and when you’re finally past that you end up getting your 9.0/9.3 dragged up to 10.0/10.3 almost every match.
Gaijin know this, they certainly see it in the stats, so I guess they want it this way. After all, if you get the premium, you can largely stop the up tiers too!