None of them conquered 1/4th of the world's population in less than a century. Just sayin'
If anything the Mongols are underappreciated, if not for the achievements of their own empire but at the least the massive impact and legacy they left behind.
I'm all for pointing out their weakness or taking a realistic approach to their study and applying that to alternate history; sure yeah they built a massive empire that wasn't rivaled for hundreds of years... which immediately fell apart once they stopped conquering new lands. But saying that the Count of Anhalt-Zerbst, who could at most muster a hundred men to his cause, almost all of them peasant levies who don't really care whose in charge and just want to get back to the autumn harvest, is going to stand a chance against a hundred thousand Mongol invasion army, which constitutes a "scouting force," because of the trees, or because it's a little rainy, it's just ridiculous. It ignores not only the historical record, which in and of itself is something of blasphemy if you're wanting to take a realistic approach to alternate history, but all logical sense, in favor of applying some sort of weird Eurocentrist feeling that somehow Europe was special and surely the righteous Europeans would have fought off the dirty hordes simply because they're European and therefore inherently different or superior.
Except my issue is with stuff like the hundred thousand claim, you ignore German claims that some random count could muster 10,000 men but you just accept without question that the Mongols could take 100,000 men, ten times what for the German count is a ridiculous exaggeration (which it was, I can give you that). That's a blind acceptance of Mongol supremacy that I take as just fanboyish and simplified. Yes the mongols created one of the worlds most massive empires in history, but that doesn't make Batu Khan a wizard. He's still just a guy who probably has at most fifty thousand people under arms and who still needs to keep them supplied and alive while fighting in inopportune terrain for years on end.