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.
From the new system in the UCL competition, Leverkusen is only trying to fight how much strength its current performance is after last season successfully reaching the final in the European league and winning the bundesliga title. Although the competition in the UCL and UEL is different, I am sure Xabi only wants to see the strength that needs to be improved to bring Leverkusen to a higher level in the future.
I agree that Leverkusen actually has a greater chance if they want to focus on winning the bundesliga title because the stability of Leverkusen squad performance has been much better since Xabi was with them.
But anyway, we just have to see what Xabi will plan. And if they have failed in the UCL and also cannot win any titles this season, that would be even more disappointing.