Siefkes comes to Green Bay after serving as the defensive coordinator for Virginia Tech in 2025. He is entering his fifth season in the NFL, having previously worked as the linebackers coach for the Arizona Cardinals (2023-24), where in 2024 he helped the Cardinals rank No. 4 in the league in points allowed per game (19.6) and allow the fewest total TDs (20) and the fewest passing TDs (10) in the NFL over the final 11 games. Siefkes spent the previous two years as the assistant linebackers coach (2022) and as a defensive quality control coach (2021) for the Minnesota Vikings. Prior to his time in Minnesota, Siefkes was the defensive coordinator/inside linebackers coach at Wofford College (2018-20) and at the University of Wisconsin-Platteville (2016-17), a defensive graduate assistant at the University of Wisconsin (2015), a defensive/special teams quality control coach at Florida International (2014), a student assistant at the University of Wisconsin-La Crosse (2012-13) and a strength and conditioning intern at the Air Force Academy in the summer of 2013. The Oconomowoc, Wis., native played defensive back at Wisconsin-La Crosse in 2011 before injuries ended his career.

Siefkes comes to Green Bay after serving as the defensive coordinator for Virginia Tech in 2025. He is entering his fifth season in the NFL, having previously worked as the linebackers coach for the Arizona Cardinals (2023-24), where in 2024 he helped the Cardinals rank No. 4 in the league in points allowed per game (19.6) and allow the fewest total TDs (20) and the fewest passing TDs (10) in the NFL over the final 11 games. Siefkes spent the previous two years as the assistant linebackers coach (2022) and as a defensive quality control coach (2021) for the Minnesota Vikings. Prior to his time in Minnesota, Siefkes was the defensive coordinator/inside linebackers coach at Wofford College (2018-20) and at the University of Wisconsin-Platteville (2016-17), a defensive graduate assistant at the University of Wisconsin (2015), a defensive/special teams quality control coach at Florida International (2014), a student assistant at the University of Wisconsin-La Crosse (2012-13) and a strength and conditioning intern at the Air Force Academy in the summer of 2013. The Oconomowoc, Wis., native played defensive back at Wisconsin-La Crosse in 2011 before injuries ended his career.