On a Friday night at the Stadium of Light, Arsenal claimed three points with a 2-0 victory over Sunderland — a result shaped less by dominance than by the cruel arithmetic of football's decisive moments. Sunderland held their own for the better part of an hour, only to be undone by a single goal, a missed penalty, and the misfortune of a late red card that handed the visitors a second. It is a familiar story in sport: not always the better team wins, but the one that converts when the door opens.