even it was not like a prediction anymore, but more like a "certainty that will definitely happen"

Because Bayern Munich has been dominating for years. And finally when the record was broken, and it wasn't Dortmund who did it, but Leverkusen who was really not predicted before, it became a sensation and very interesting. Ah last season was really the best season in the Bundesliga.
At first we thought that if anyone could break Bayern Munich's dominance, then Borussia Dortmund was in our minds as the team that could do it. Last season they were one step away from doing it, but unfortunately they couldn't win their last match in the Bundesliga.
Honestly at the beginning of last season I didn't think that Leverkusen would be able to do all this, but they were able to confirm themselves as the team that managed to break Bayern Munich's dominance.
It seems that almost everyone even thought so, surely it would be Dortmund and not think at all about Leverkusen. But as time went by, when Leverkusen became undefeated until the 10th match, it began to explain, this club is special and should be watched out for by Bayern Munich. Bayern Munich may not have intended to underestimate Leverkusen's achievements at first, but there were indeed several matches where Bayern Munich missed the point, did not compete optimally, so that the first position was in Leverkusen. Maybe Bayern Munich thought that soon Leverkusen would lose and they would take the first position again. But that did not happen.
in fact, Bayern Munich was the one who lost again, while Leverkusen? they survived until the end of the match, undefeated. This is what Bayern Munich did not expect either, so this season they will definitely not waste this opportunity again, they are increasingly aware that their competitors are not only Dortmund, but there is actually something more worrying even though secretly, not only Leverkusen, but also Stuttgart.