LSU The next time Barnett interviewed with Saban, it was for a graduate assistant opening on Saban's
LSU football staff. In Barnett's sole season as a GA at LSU, the Tigers won the
2004 Sugar Bowl (
BCS National Championship Game).
Cincinnati The following season, Barnett was hired as defensive backs coach at the
University of Cincinnati under
Mark Dantonio.
Return to Michigan State Barnett returned to Michigan State in 2020 to coach the secondary. When head coach
Mel Tucker was suspended and then fired in September 2023 over a sexual harassment scandal, Barnett succeeded him as interim head coach.
Jonathan Smith was hired as the permanent head coach that November. Barnett was one of two coaches (Courtney Hawkins) retained on the new coaching staff by Smith.
Player development Barnett is known for his success in developing players at the
University of Cincinnati,
Michigan State University and
Florida State University. In three seasons at Cincinnati, Barnett coached four defensive backs to all-conference honors. For Michigan State University, Barnett has coached 10 Spartan defensive backs who have been selected in the
NFL draft, two of whom were first-round picks (
Darqueze Dennard, No. 24,
Cincinnati Bengals,
2014; and
Trae Waynes, No. 11,
Minnesota Vikings,
2015), four All-Americans, three
Thorpe Award semifinalists, and one Thorpe Award recipient. During his time with Florida State University, Barnett coached five players who earned All-ACC recognition, a
Bednarick Award semifinalist, and five players selected in the NFL Draft (
Brian Burns, No. 16,
Carolina Panthers,
2019;
Asante Samuel Jr., No. 47,
Los Angeles Chargers,
2021;
Janarius Robinson, No. 134,
Minnesota Vikings,
2021;
Joshua Kaindoh, No. 144,
Kansas City Chiefs,
2021;
Hamsah Nasirildeen, No. 186,
New York Jets,
2021). ==Personal life==