Sometimes I 've noticed that an injury is coming with a drop of moral. I don't know if this is causing the injury or the injury did this.
A significant drop of moral it's a sign that the player is coming in a de-form period so maybe that's why your ST doesn't score.
A ST with rates of 7 who doesn't score, is out of form (while, a 7 is a descent rate for a MC or a GK).
That's my personal experience and point of view