Anyone ever heard of it? Evidently when the birds are very active and flap their wings a lot it will cut off blood supply to the breast"tenders"and it will muscle will die and turn a green and wood like fiber. Buddy killed one yesterday. First I've ever heard of it
I can't tell too much about the picture. But it looks to be not very deep in the breast which to me would be an injury. But injury is usually purple, blue, or reddish and not green.
In hot weather, they will sort of internally "cook." The area between the tender and breast, or underneath it close to the keel bone is somewhat common to find if you don't breast it or clean your bird in a timely manner. This will cause this discoloration and also the woody type appearance and texture.
Woody breast in poultry is from the muscles growing too fast. Normally… but like you said stress, heat, and activity can also cause it to be woody. Never seen woody breast in a wild turkey. But it does happen in the poultry industry. It chews like wood and actually looks like wood.