We don't yet know for sure whether the team's performance will decline if several of the brand's main players are injured because it could be that there will be a cover that can cover if player rotation occurs in order to maintain the team's performance, because the team should be able to do that.
So far, Bayer Leverkusen is still quite strong and consistent, regarding bad incidents (injuries) to players in the future is something that cannot be predicted, but if we look at almost all lines, they have players who have even quality so it is possible for them to maintain performance.
But what often happens is that when a key player is injured, the team begins to see a decline, even though it is not too deep, but often when facing an important match, they actually experience defeat or results they don't expect, even a team as great as Manchester City experienced this when Kevin DeBruyne was injured despite the intelligence of their coach succeeded in closing the gap left by KDB with the right players so that City could recover, but if there is quite a difference between the reserve players then slowly teams that face injured players and also have to play in several competitions will end up sacrificing other competitions and focusing only with just one competition.
We have to see Bayer Leverkusen play several matches to be able to judge that their players' injuries do not affect the team's performance. If they start to lose then it is evident that the player's injuries are disturbing the team, but because they are safe in the European league and the team they are facing can be said to be below their quality compared to them, the remaining two matches would not be a problem if the result was only a draw, because Bayer Leverkusen has confirmed that they have passed the group phase.
It is very true that injuries experienced by key players can cause decline in performance which can even be quite significant and so far there have been quite lot of strong teams who have lost core players due to injury and then they experience decline in the quality of in playing, what is even worse is that this decline causes several defeats.
Even so, there are still one or two teams that are not too affected by the presence of injured players, but teams like this are usually teams with players who are all said to be great players and they have truly become perfect squad.
When an injury occurs to core player, there are still other players who can provide stability and there are also reserve players who can at least have equally good playing qualities.
Like Real Madrid, they experienced conditions like this but the decline in performance was not that significant.
Moreover, Leverkusen will only play against Hacken which is the team in the bottom position in group H and in four matches they have not won single win, I still believe that Leverkusen is able to win this match despite the shortcomings they are currently experiencing.