I understand the theory

it just does not hold water.

Take a look at this photo and tell me that it is possible to get into this position without fully cocking the lead wrist:


I have tried this sort of thing many times in front of a mirror the only way to get to this position without cocking the lead wrist is to setup with the hands very low with the lead wrist fully cocked. It is not perspective the lead wrist is cocked.

Also flat is flat and cupped is cupped. DJ's lead wrist is flat at impact not cupped or neutral.

Regards, Herbert