First Ömer Toprak left Leverkusen, then Hakan Calhanoglu, now Chicharito. With other key men likely to follow them out, is there any hope that a club that's become a fixture in the top four can stop the rot next term?
"It was not a difficult decision." Those were the words of Javier Hernandez (aka Chicharito) as he pulled on a West Ham shirt for the first time after completing his move back to England on Monday. He seemed to be referring mainly to the decision to join the London club rather than the one to leave the Werkself, but the sentiment seems applicable to both cases.
The Mexican striker endured a difficult end to an otherwise prolific Bundesliga career, as the service dried up in a team desperately struggling to keep their heads above water. Leverkusen suffered through a desperate second half of the season, winning just four league games after the winter break until a cathartic 6-2 defeat of Hertha Berlin on the last day of the season, after safety was assured, gave them a measure of relief.
That win also meant they finished 12th, a position that flattered a side that looked woeful under Roger Schmidt and even worse during the short-lived reign of Tayfun Korkut. It was all a far cry from Chicharito's debut campaign for the club, when he scored 17 times in 28 appearances and was the league's player of the month three times, as Leverkusen picked up the "best of the rest" trophy behind Bayern Munich and Borussia Dortmund - about the best the other Bundesliga clubs can hope for these days.
Where will the goals come from?
However, thoughts of challenging for even that dubious crown seem fanciful at this point. Chicharito may well have wanted out whatever happened but the departures of Hakan Calhanoglu, who provided a goal or assist every 110 minutes last term in an interrupted Bundesliga campaign, and Ömer Toprak – a defender good enough to step up a level to BVB - must have made him question the club's ambition.
Of course, there's still plenty of time in the transfer window (though Leverkusen's first German Cup game is in a little over a fortnight) but Sven Bender and Dominik Kohr don't feel like upgrades. Bender may offer some defensive stability, which would be further enhanced if Jonathan Tah can regain fitness, but it's going forward that Leverkusen look set to struggle.
No-one but Hernandez even reached double figures for goals in all competitions last term and removing Calhangolu from the equation as well means only Kevin Volland (9) and Joel Pohjanpalo (6) scored more than 4.
It's no wonder new coach Heiko Herrlich, the club's eighth boss in nine years, has been preaching the virtues of teamwork over individuals.
Teamwork the key for new boss
"Hakan of course has huge quality, as do Kevin [Kampl, who has also asked to leave] and Chicharito," he told the Bundesliga website before the Chicharito deal went through. "But ultimately it’s important that the players that you have available identify 100 per cent with the club. Things will soon be clear - then we'll see more.
"I think a club like Bayer Leverkusen will never find themselves depending on just one player. Chicharito has given great performances in his two years here, but so have many others. You can only achieve success as a team."
Perhaps Herrlich will forge the collective identity that the side lacked last year, but even the hardest working sides need matchwinners.
Leverkusen have become a fixture at the top end in recent years, never failing to finish outside the top five in the seven years before last. But with the emergence of Leipzig and Hoffenheim and even Hertha Berlin and Cologne starting to make small but significant strides, it's becoming more and more difficult to see a way back to the Champions League for a club who famously reached the final in 2002.
Perhaps that's not the expectation anymore and perhaps they can hang on to a small but talented crop of youngsters - Tah, Julian Brandt and Kai Havertz chief among them - and make progress that way. But, as Dortmund found out last term, it's not easy to cope with losing three key players in one stroke.