COMMERCE CITY, Colo. — Head coach Emma Hayes made a successful debut with the U.S. women’s national team, watching Mallory Swanson and Tierna Davidson both score twice in a 4-0 win over South Korea on Saturday in a friendly match.

The U.S. squad steadily found its rhythm, with Swanson and Davidson breaking through in the first half and again in the second.

At times, Hayes paced along the coaching box as she looked on. She clapped on goals and near-misses. Sometimes, she retreated over to…