 The Kansas City Chiefs switched to a hybrid 4–3 defense in the 2019 season with the hiring of new Defensive Coordinator Steve Spagnuolo.The Pittsburgh Steelers have used the 3–4 as their base defense since 1982, the season after Hall of Fame defensive tackle Joe Greene and end L. C. Greenwood retired.In fact, the Steelers were the only NFL team to use the 3–4 defense during the 2001 NFL season, but finished the season as the number one defense in the NFL.