I don’t think you understand.
Most of these people one-spawn their tanks.
If they don’t spawn in when it’s a full uptier, their team position goes down since it is calculated based on the average team position every match.

Let’s say there’s 10 people on your team.
If you play 5 matches and 2 of them are full uptiers, you will have 2 of those matches be 10th place (0%)
Then let’s say they do really well on the other 3 non-full uptier matches because they are really good.
1st place on each of those 3 matches.
Their average team position won’t be 100% but 60%.
Most of the people I’ve been checking have at least ~80%, so unless they’re not getting uptiers in their KV-220 somehow, they’re not only playing in downtiers.
Here’s an example:

Here’s an example of a person only playing full down-tiers:

Gaijin being Gaijin?
Remember when I told you sample size (and quality) matters?
E-100 is a very special vehicle – only being able to be played by the best players or those that pay a lot of money.
As a result, the average user is really good, and therefore the E-100 only has 3100 games played throughout December, and is why you get such a disparity.

Looking at the Maus, it’s way less special, being able to be played by anyone who has at least Rank IV Germany researched. Though it’s still more special than popular premiums / tech tree vehicles, so its stats are slightly boosted as a result of the fact that its average players would typically be slightly more competent.
Now look at how many games have been played just this December:

No wonder it’s significantly lower than the E-100’s.
The average Maus player is garbage compared to the average E-100 player.
If an average player of equal skill played either of them, you’d see a much smaller difference, though the E-100 may still perform better because it’s more mobile.
Since I’ve answered your question, why don’t you answer mine?