By the time Sanchez entered the eighth grade, he had developed an interest in football but was unsure of what position to play. His father consulted coaches Bill Cunerty, who formerly coached at Saddleback College, and Bob Johnson, the head coach at Mission Viejo High School. Both coaches stated Mark could be a quarterback if he applied himself and was open to learning the intricacies of the position. Nick Sr. trained Mark during sessions in their backyard or at the park. Mark, who was attending Santa Margarita High School, joined the football team. During his first pass attempt as a sophomore, Mark threw a 55-yard touchdown.