Originally Posted by Andre Yew
On a real person, that indentation is usually caused by the jacket's shoulders being too narrow. In this case, it kind of looks wrinkled.
I'm not sure that I understand how that could be.
If the shoulders were a bit "tighter", the upper arm would fill the sleeve head, and fill the dents on the sleeves. If the shoulder seams fall at exactly just beyond the end of the shoulder bone, then there is some "shoulder" and arm extending past that to fill the sleeve head.