In my opinion, whether or not they have popular players for a club is not a big problem, provided they have good teamwork, because in football what is more important is teamwork and also the chemistry between players. For now, Leverkusen can show that, even though they don't have many big names, collectively, in my opinion, their team is better than Bayern Munich.
It is natural that Bayern Munich has good teamwork, because the players they have are above the average for clubs in the Bundesliga. Their second line of players is no less good than the main players.
Meanwhile, Leverkusen doesn't have that, with a composition of players that is no better, even as a coach, they only have Xabi, who in terms of experience is very different from the Bayern Munich coach, but Xabi can make very interesting games for Leverkusen.
Leverkusen do not really have big names but they have so far by their performance made name for themselves even amongst them a few players have begin to gain attention because their performance are now exceptional and are deserving of the attention they are beginning to get, players such as victor Boniface has gained some attention resulting from his performance.
Like you have stated correctly some times it's not about the big names you have got in your team but how well these players have got the team spirit and are been managed well enough to deliver the desired results required of them because if they are all playing for individual glory they will find it really difficult helping the team move forward because they want to set individual records which at times it turns out at the detriment of the team, Leverkusen's teams spirit has really helped them a lot no doubts and so far they will make good team even after this season if the players don't get sold.