Underlords is weird with scaling. The more you play, the more you'll see that happen. Someone goes on a massive losing streak and ends up at 20hp, then somewhere down the line, they get the unit they need and everything clicks. They come back, go on a massive winstreak, and end the game at 20hp.
I'm trying to figure out a way to have such a scaling effect, while also having decent early game. Units like Bloodseeker at 2* really really helps, as does an early Inventor package, and Queen of Pain, which can easily get you through a ton of the early matches and get to late game where you can start actually working on your comp