First, no, players of a race do not have to have imbalanced win rates for their race to have deviated MMR. They can have a population difference instead: Suppose that Silver is 20% Protoss but all other leagues are 33% of each race, with 50% win rates.
Protoss average MMR would be inflated from this, but that doesn’t mean - inherently - that there’s something wrong.
And, no, “X rank is (not 33%) of a race” does not mean that there’s anything wrong - after all, the game is 37-38% Terran when counting random separately (7-8%). We should expect to see that carry over, that 37% of each rank is Terran.
As you go up the ladder, Zerg players steadily increase, while Terran players decrease but spike in Diamond but Protoss population has a sine curve on its bars. That’s got dozens of possibilities by itself.
But, and most importantly: No. The reason Terran MMR is on average trash is not because they lose more. It’s because there’s many more of them at lower ranks. The percentage of Terrans in Silver, Gold, and Platinum - all Leagues whose win rates are 50% - is significantly higher.
While, yes, you could argue that that’s because the system is bumping them until their win rate stabilizes near that 50% mark - and I would not be able to actually disagree - the thing that that data suggests to me is the following:
Terran is the easiest race to get an initial handle on, to understand as a player still learning the game’s flow.
What this, in turn, means, is that of the players who will be bronze this season because they are currently bad at the game, for a number of factors, choose to be Terran - We’ve gone over these before, but once more:
• Its mechanics are intuitive for most, and those mechanics are present in most RTS.
• Its tutorials do the best job of explaining how the race works. The Wings campaign works very like ladder Terran, but the Heart and Legacy campaigns don’t. The tutorial game nuances fail to prepare you for Zerg, and Zerg’s production generally is a big stumbling block for players*.
• Its unit advantages and play aides - Bunkers, Tanks, repair - are things that players feel greatly comforted by the safety of, and therefore will pick more often.
• It’s also the humans, and there’s a lot of people who will pick the race because it is the humans, whereas the people who will pick a race because they don’t want the humans are divided in two.
• Bio is ‘hype’ so there’s a fair contingent of people who want to learn how to do the cool hype splits and devastating comebacks - except don’t have the mechanical foundation for that so it doesn’t work.
In a sense, this boils down to this:
Bad players are more likely to be comfortable with, and therefore play, Terran.
Which I repeat despite being something that last time I said it you insisted it said something it didn’t say, because I have studied this to the degree that is particularly feasible for my personal range of influence (<200 samples).
However, these statements have already been said, the quoted line’s relevancy disputed at length only for you to almost entirely ignore it when those rebuttals got originally posted. :\
*As a note, because I like notes, being pissed at Heart of the Swarm’s babying was actually the thing that made me care and have tracked this information a few years ago. I was infuriated because it took three missions to explain stuff that Wings basically didn’t bother explaining – but then getting other peoples’ opinions and watching them play really let me realize that, no, Zerg macro just is weird and hard to parse for quite a few people.