Regardless of luck, the best rises to the top. Take Cups, the teams know as the best win it 99% of the time. And with leagues, the best team that season end up winning.
There is luck on a match to match basis but over the entire course of the season, they usually balance out.
Coutinho is a good player but he’s not as amazing as the hype made him out to be. The price was way too high. Even at Liverpool, he wasn’t as amazing as fans made him up to be. He was okay in most games but every 3 or so games, he’d produce some bit of magic.