Performance in the 1900s and 1910s isn't going to impact much analysis of them post-World War II.

For why:

1. Ability to raise pretty large armies.
2. After WWII they controlled (or at least had controlled by aligned governments who couldn't afford too much of a breach with them) a vast amount of land and its resources, much more of Europe than any Russian empire ever had.
3. A lot of nuclear weapons and the ability to deploy them at a lot of targets.
4. They had considerable ideological appeal to a lot of the world.
5. They did inflict a lot of casualties on Germans and their allies.

Now it's not as though failures didn't get noticed. In fact, Finland was so embarrassing that they weren't expected to put up a good defense against the Nazis. That they could push Germany back, even if it required a lot of logistical support from the US and came about alongside invasions of Italy and France, goes to show that a weak military doesn't necessarily stay that way if there are the right motivations and it has time to change.