STARKVILLE — Mississippi State football head coach Jeff Lebby has named Zach Arnett the Bulldogs’ defensive coordinator, returning one of the nation’s most productive defensive minds to Starkville. Arnett previously served as Mississippi State’s defensive coordinator from 2020-22, coordinating three consecutive top-five SEC defenses before being elevated to head coach in December 2022. He spent the last two seasons as an analyst at Ole Miss (2024) and Florida State (2025).
Arnett returns to lead a defensive unit that aims to reestablish its physical, aggressive, attacking-style identity.
Across his three seasons as MSU’s defensive coordinator, Arnett’s defenses ranked top five in the SEC in 28 different defensive efficiency and production categories during that span, including finishing No. 5 in the league in total defense in each individual season. His units also finished No. 3 in the SEC in limiting explosive plays, No. 4 in turnovers forced and No. 5 in points per possession allowed.
Mississippi State also posted top-five SEC marks in scoring-drive percentage allowed, touchdown-drive percentage allowed, yards per play allowed, opponent quarterback rating, red-zone defensive efficiency and non-scoring drives forced. Arnett’s defenses excelled situationally as well, ranking top three in front-seven efficiency and top five in both inefficient plays forced and possessions ending in a turnover, three-and-out or fourth-down stop.
In his four years at Mississippi State, Arnett produced seven NFL Draft picks, including linebacker Nathaniel Watson (sixth round), cornerback Decamerion Richardson (sixth round) and defensive tackle Jaden Crumedy (sixth round) in 2024, defensive back Emmanuel Forbes (first round) and Cameron Young (fourth round) in 2023, cornerback Martin Emerson (third round) in 2022 and defensive lineman Marquiss Spencer (seventh round) in 2021. Under Arnett’s leadership, Watson, Forbes and Emerson also earned All-America honors.
Before arriving at Mississippi State in 2020, Arnett served as defensive coordinator at San Diego State for two seasons. In 2019, the Aztecs finished top 10 nationally in seven major defensive categories, including second in rushing defense, third in scoring defense, fourth in interceptions, fourth in first downs allowed, sixth in total defense and eighth in takeaways. His 2018 unit also ranked among the national leaders in run defense, first downs allowed and total defense.
Arnett spent nine seasons at SDSU overall, beginning as a defensive graduate assistant (2011-13) before coaching linebackers (2014-17) and ascending to defensive coordinator. During his tenure, the Aztecs won three Mountain West championships and appeared in nine straight bowl games. He coached seven all-conference linebackers, including All-American Calvin Munson.
A former linebacker at the University of New Mexico, Arnett was a four-time Academic All-Mountain West selection and a 2008 CoSIDA First-Team Academic All-American. He recorded 200 career tackles, tied for the FBS lead with six forced fumbles as a senior, and helped the Lobos to 25 wins and two bowl appearances.
A native of Albuquerque, New Mexico, Arnett earned his bachelor’s degree in history with a minor in political science from UNM. He and his wife, Emily, have two children: son Case and daughter Collins.
Lebby on Arnett
“Zach is one of the top defensive minds in college football, and we are excited to welcome him back to Mississippi State,” Lebby said. “His defenses here were tough, disciplined and among the most productive in the SEC. He brings energy, edge and a defined identity to our defense, and I’m confident he will help elevate our program immediately.”
Arnett on Returning to Mississippi State
“I’m grateful for the opportunity to return to Mississippi State and lead this defense,” Arnett said. “This place means a great deal to me and my family, and Starkville has always felt like home. I’m excited to get to work for Coach Lebby, support his vision and do my part in contributing to the program.”
Arnett Coaching History
2025 – Florida State, Analyst
2024 – Ole Miss, Analyst
2022-23 – Mississippi State, Interim Head Coach/Head Coach
2022 – Mississippi State, Defensive Coordinator/Safeties
2020-21 – Mississippi State, Defensive Coordinator/Linebackers
2018-19 – San Diego State, Defensive Coordinator/Linebackers
2014-17 – San Diego State, Linebackers
2011-13 – San Diego State, Graduate Assistant (Defense)
