but then look at that interesting table, which reveals that leverkusen do barely make use of their own academy players (or were unable/unwilling to), with christoph kramer being their only self-made academy offspring who has in fact any bundesliga experience, or any name to him, for that matter - though he was in fact developed to his prime during his two-season loan spell at gladbach, under lucien favre:
number of home-grown players in the squad
SCHALKE:
12 (697) <- collective bundesliga appearances for the home club
BREMEN:
11 (175)
FRANKFURT:
8 (331)
DORTMUND:
7 (634)
HANNOVER:
7 (8)
STUTTGART:
7 (312)
HOFFENHEIM:
7 (69)
BAYERN:
6 (707)
GLADBACH:
6 (365)
WOLFSBURG:
6 (138)
HERTHA:
6 (98)
AUGSBURG:
6 (0)
COLOGNE:
5 (59)
LEVERKUSEN:
5 (2)
MAINZ:
5 (70)
DARMSTADT:
4 (0)
HAMBURG:
3 (10)
INGOLSTADT:
1 (0)
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leverkusen's current generation of young, exciting starlets have been brought in from other clubs, at some point, when most of them had already made it into a senior squad and had at least minor experience in competitive top-level matches - except for julian brandt, who had only gone through wolfsburg's academy, though widely deemed to be one of germany's brightest u-18 talents, before he went on to sign his first professional contract at leverkusen.
schalke, on the other hand, have continuously managed to develop (and make proper use of) a seemingly neverending crop of self-made, gifted youngsters.
those 12 home-grown players in their squad are the following: höwedes, matip, draxler, fährmann, meyer, kolasinac, sané, ayhan, marvin friedrich, platte, kehrer, multhaup - that's SEVEN players with ambitions for a starting spot!
as it might be of interest:
dortmund's seven home-grown players are sahin, reus, schmelzer, großkreutz, dudziak, duksch and stenzel.
their approach seems to have switched to bringing in more external talent at a rather early stage, scouting all age groups from u15 to u19, or so it appears, on an international level as well. here's more on that:
http://constantineckner.com/2015/04/the-future-of-borussia-dortmund-is-secured/
bayern's six home-grown players are lahm, müller, alaba, badstuber, gaudino and greene.
- - -
ps. the above table is of course jaded due to some clubs being feeders to other clubs, what with geis from mainz to schalke, or sinan kurt from gladbach to bayern, or sarr from leverkusen to dortmund, or selke from bremen to leipzig, and so on. plus richer, bigger clubs have a broader network and outreach, as well as simply much more money when it comes to talent scouting and luring away other clubs' most promising players, be it regionally (see stuttgart, schalke, hamburg, leipzig for example) or internationally (see leverkusen, dortmund etc)