Karl-Heinz Rummenigge believes Schalke could have been Bundesliga champions in recent years had they not lost so many talented young players.
After a promising first half to the 2019-20 season, Schalke endured a wretched run of results either side of the break in the campaign due to the coronavirus pandemic, failing to win any of their final 16 games to finish 12th.
There have also been issues off the pitch, with chairman Clemens Tonnies resigning following fan protests, while marketing director Alexander Jobst has confirmed there will need to be cuts due to the financial situation the club faces.
Yet their situation could have been different had they retained some of their rising stars through the years, according to reigning champions' Bayern Munich's chief executive Rummenigge.
Among those to move on were goalkeeper Manuel Neuer and Leon Goretzka, who both went to Bayern. The duo will be joined at the Allianz Arena next season by two more talents developed by Schalke, goalkeeper Alexander Nubel and Leroy Sane, the latter this week confirming his switch from Manchester City.
"Schalke could have been German champions in the meantime if they could have kept these and many other players who have trained them well in their youth division," Rummenigge told Sport1.
"The pool of their youth work is one of the best in all of Germany.
"The fact is that they have always sold very hopeful players, such as Leroy Sane to Manchester City in 2016, to meet their financial needs."
The COVID-19 health crisis is likely to have major financial implications on the vast majority of football clubs, even those seen as the biggest spenders in Europe.
Rummenigge revealed Bayern have never planned their budget around potential success, instead setting a relatively low bar each season to make sure they have long-term security.
"Until February, this was one of the safest [clubs] in the world," he said.
"If the team performed by reaching at least the last 16 in the Champions League and going very far in the DFB-Pokal, then they knew we always on June 30 that the year will be financially okay."