I have hardly ever had a problem with expedition until very recently. Recently I've been running into groups way beyond what I can handle, even after hiring a maxed out character from another.
I'm not sure what it goes by for the teams you draw, but the other day I accidentally hit the max level button (there really needs to be a confirmation process here), and ever since then I'm lucky if I can make it beyond the second or third round. And this is after consistently beating all rounds every day for years.
This makes me not even want to try in expedition. Which has a negative effect on other aspects of my game (harder to compete in events, longer time to unlock skins and legendaries for some, and lower expedition rewards for shop).
This kind of stuff has me really thinking about just quitting completely.