Bayern Munich chief executive Oliver Kahn believes the key to making the Bundesliga more competitive is for German sides to improve in the Champions League first. Bayern won their 10th straight Bundesliga title this season, leading to complaints about the lack of excitement at the summit of the German top flight. In contrast, Bayern went out in the Champions League last eight with other German entrants long gone. “More top stars in the league, excitement at the top, that helps sell TV rights at home and abroad. And it is precisely here that we have recently lost ground dramatically,” Kahn told…