You're just assuming which what am not sure about Leverkusen where they give more priority to either the UCL or the German bundlesliga. Your conclusion I believe is based on how Bayer Leverkusen are doing far better in the UCL than they are in their domestic league but sometimes that's how things could go for a club, they may not be able to give a good and strong performance on all competitions. Basically, Leverkusen has a better chance of winning the bundesliga trophy this season than they would in the UCL, so for me, your conclusion don't hold much base in my opinion.
He has the same base that the champion teams have, Real Madrid thinks like this and if you look at Xabi, he also comes from a team like Madrid, he already has his Bundesliga, he would have won his Europa League but he couldn't, but now that he's in the UCL he doesn't want to waste his opportunity, maybe he looks after his best players or plays in a different way in the league focusing on the UCL, that's my base, because if they were putting all their energy into it, the results in the Bundeliga would be different, it is known that the UCL has a much higher level, the best players from all the leagues are there, therefore more demand, more strength, more speed, more wear and tear, but if they manage to win the UCL where technically it is possible, that prize is worth a lot to a team.