Leverkusen has a busy schedule and is a short distance away. I am worried thats this will affect Leverkusen performance when facing matchs in the Bundesliga. However, Xabi Alonso must focus on his players and have a way so thats his player don't experience decline in performance when facing match in a short times to remain in first place, of course Xabi Alonso will try hard so that Leverkusen is not shifted from its current position.
Definitely their performance will be affected playing games at very short intervals they definitely stand the risk of facing fatigue or strain, although at the moment they don't have an injury prone player so they wouldn't be so bordered about possible injuries from the games but then their will be a slight drop in performance but they could possibly manage it to still maintain a good position at the end of the day.
They could prioritize the game by their level of importance and know for which game they should rest player possibly and the game they wouldn't engage so much so as to control possible chances of fatigue and injury, for their bundesliga game if they get a draw they will be one point behind and if Munich gets a draw aswell they will still remain safe but if they draw and Munich wins dey will drop to the second position most likely.
Leverkusen has been in their best of form this season so I'm hoping they will be able to manage it and still come out strong maintaining their position after which they will have enough time to rest and probably recover from the series of games which could pose some level of stress on them, I personally will suggest they prioritize their bundesliga games and place less priority on the Europa games as they will be facing Molde first in the Europa game before their bundesliga game and molded happens to be a weaker team so it will give them less stress as compared to their bundesliga games.