I had read the following quote before but not read that it had activiely been used in the lead up to WW2:

I divide officers into four classes -- the clever, the lazy, the stupid and the industrious. Each officer possesses at least two of these qualities. Those who are clever and industrious are fitted for the high staff appointments. Use can be made of those who are stupid and lazy. The man who is clever and lazy is fit for the very highest commands. He has the temperament and the requisite nerves to deal with all situations. But whoever is stupid and industrious must be removed immediately."

Attributed, circa 1933
General Baron Kurt von Hammerstein-Equord (1878-1943)
German Chief of Army Command (1930-33)
Then we have the following explanation which does not seem to have the proper attributes but nevertheless makes interesting reading:

German Army officer selection

If there is more detail on this out there it would be appreciated...