It is still too early to talk about the luck factor in the Europa League this season because there are still many strong teams in the Europa League this season who may still be able to beat weak teams to become champions in the Europa League. For example, like the two teams you mentioned, Leverkusen and Liverpool will definitely dominate the European League this season to win the title with the abilities they each have at the moment.
Luck factor is still very considerable because we have seen so many scenarios where teams that are not expected to go far in a tournament end up winning the competition by luck not by the strength of their squad because if we wants to consider their squad they can never go close to winning the league.
Liverpool and Bayer Leverkusen are actually the strongest teams in the Europa League so far, and from the beginning of the tournament, their performances have been top notch which is why they are considered as the favorites to win the Europa League. UEFA Champions League teams like AC Milan and Galatasaray come with another strong team to give us more competition in the tournament, as a result of that, the luckiest team will emerge the winner this season.