ATRs are notoriously difficult to keep straight on the runway owing partially to the narrow MLG track. Additionally on high wing turboprops if you bring the power levers back into the disc position quickly (easily done with a bit of adrenaline in the system after a challenging approach) you can rapidly lose rudder authority as you disrupt the airflow over the vertical stabiliser and rudder, allowing the aircraft to weathercock and take a beeline toward the upwind side of the runway. It will be interesting to see which side of the runway the excursion was on.