You should also check their performance in their own domestic league in this season, both Bologna and Girona performance are terrible, while Leverkusen is still fine even though not as strong as in the last season. But, Leverkusen met easier opponents, like Milan and Feyenoord, which is nothing surprising they can won those match.
After all we still have many upcoming match, Girona is quite lucky their opponent not that strong.
I have seen Bologna and Girona playing badly unlike last season, both teams in their domestic matches had very doubtful performance while Leverkusen was very lucky that the opponents they faced were not at the level of a strong team this season.
Leverkusen has shown their best at the start of this season and the group Leverkusen will face Milan and Feyenoord in the grub phase, making it very easy for them to get points. The match has just started, let's wait for the next match.
Bologna and Girona do not have as big a chance as Leverkusen in the Champions League, because in my opinion Leverkusen is on a different level in terms of quality from the two teams. Leverkusen has clarity in strategy, the point is there is a vision that can be seen when they play on the field. Girona and Bologna only performed well last season and are not necessarily able to do the same. So if you look at the probability, Girona and Bologna will be eliminated from the Champions League competition faster. Tickets in the play-offs are also not a guarantee to be able to go further.