T8 matchmaking is broken but I think it has a lot to do with the time of day that I'm playing. Most often I'm on when server population is around 6000. During this time I'll be lucky to get top tier, maybe 1 in 6 games? However it doesn't seem to impact my 50% WR just that my grinding is taking longer to get Tier 9 tanks.
Edit: forgot to add that I don't think they should mess with MM any further. Unless they can come up with some way to check how many games per tank you've had as bottom tier and then put you in top tier. For example it feels like I never get top tier when I'm in my Skorp G.