A man walks into the doctor’s office with a duck on his head.
The doctor asks, “Can I help you?”
The duck says, “Yeah, Doc, can you please get this guy off my a**?!”
My latest epiphany about the handling of French Defense positions where White has advanced the king’s pawn to e5 is that it’s like getting the guy off the duck. No subtle positional scheme is involved. Black works crudely to get liberated from White’s cramp by any means possible. When that has gone as far as it can go, Fischer’s Rule of Reciprocity, “You gotta give squares to get squares,” applies, and Black opportunistically utilizes those squares White has neglected in his struggle to maintain the bind.
Here’s a salient example from the Zurich Chess Challenge in February, 2016 wherein Hikaru Nakamura quacks up Alexei Shirov. In the final position, it’s all over after 39. Kxh2 Qh5+ due to tactics based on the discovery on the White queen.