When you lack composure, you are easily startled.
This leads to hurrying. And anxiety.

Instead of patiently waiting to see what unravels, you dither, hesitate and anticipate.

Rushing indicates a lack of competence.
It is obvious that the student has not put in the practice.

When you rush, you force.
Forcing causes your opponent's nervous system to inadvertently tense-up in reaction to your urgency.
This alerts them to your intention and makes them harder to manipulate.