Derrick Johnson is in the College Football Hall of Fame. He played 13 seasons with the Chiefs, earning spots in four Pro Bowls. Yet on Saturday, he enjoyed a career moment just by giving a speech. It wasn’t any speech. Johnson returned to the University of Texas and gave the commencement address at the College of Education’s graduation ceremonies. His mother, who worked as a teacher for four decades, was in the audience. Johnson earned his degree in 2020, 16 years after he left school. Saturday’s commencement address was Johnson’s 20-year anniversary of his senior season, when he won the Butku…