"And he saw that he had not power to hurt him." Targum Pseudo-Jonathan (Genesis 32:26) pauses to notice something the plain verse whispers but does not say outright: the angel lost.
The wrestler who came in the night — whom the Targum identifies as Michael — could not overpower Jacob. So he resorted to the one thing left. He touched the hollow of Jacob's thigh, and the hip socket was dislocated, distorted by the struggle itself.
The theology of the wound
The rabbis read this as a mystery: why does an angel of God need to cripple a patriarch? One answer: he did not cripple him out of malice. He marked him. The limp was evidence of the encounter — a scar that testified Jacob had survived something no one else had survived. Every step afterward would be a sermon.
Another reading: the hip dislocation represented the breaking of Jacob's old self. The man who crossed the Jabbok at dawn was not the man who had entered the night. He walked differently because he was different. The name change would come next; the limp came first.
The takeaway: the most honest people you meet usually have a limp. They fought through the night, and they did not come out unchanged.