Barbour joins the group as USC searches for a new athletic director.
Michigan State confirmed the alteration after ESPN first reported the date change.
Grunkemeyer is the first quarterback to join Penn State's recruiting Class of 2024.
Swoffard comes to Penn State with 20 years of coaching experience, including five separate assistant coaching gigs at different programs.
Cooper announced that he will step down after 10 seasons with the Nittany Lions.
Jack Fracyon, Matt Traynor, TJ Malone, Jack Posey, Grant Haus, and Kristin O'Neill were all named to All-American teams.