There's an element of luck to the prem, one decision can change a game and one game can change a season. But, there's a much bigger element of luck in a knock out competition, Liverpool mhave done really well, but you can't tell me they're one of the 2 best teams in europe.
All the big teams got paired off against each other in the 2nd round paving the way for the likes of PSV to get to the semi's when they finished 2nd in Arsenals group. And they were probably unlucky not to get past AC Milan.