Sean Duggan joined the Miami Dolphins as defensive coordinator in 2026. The 2026 season marks Duggan's 12th year of coaching and his third in the NFL.

Sean Duggan joined the Miami Dolphins as defensive coordinator in 2026. The 2026 season marks Duggan's 12th year of coaching and his third in the NFL.

Duggan came to Miami after spending two seasons with Green Bay (2024-25), where he served as a defensive assistant in 2024 and linebackers coach in 2025. During that span, the Packers ranked ninth in both total defense (313.2 yards per game) and run defense (108.5 rushing yards per game), and sixth in yards allowed per carry (4.1).

Despite several injuries to the unit in 2025, Green Bay's defense finished in the top half of the league in total defense (311.8 yards per game), yards allowed per play (5.0), yards allowed per rush (4.2), pass defense (194.1 yards per game) and third down defense (39.4%).

Duggan mentored linebacker Quay Walker, who led the team in tackles in 2025 while ranking 17th in the NFL with 128 stops. Linebacker Edgerrin Cooper topped 100 tackles for the first time in his career, finishing 28th in the NFL with 117 stops (63 solo). He added a half sack, four tackles for loss, four passes defensed, two forced fumbles and a fumble recovery, becoming one of only five players in the league to hit those marks.

In his first season with Green Bay in 2024, Duggan was part of a defensive that helped the Packers rank fifth in both total defense (314.5 yards per game) and yards allowed per play (5.2). The Packers were one of just three teams in the league to allow fewer than 100 rushing yards per game and fewer than 4.0 yards per carry in 2024 (Baltimore and Denver). They were also one of only two teams to record more than 45.0 sacks and 30-plus takeaways that year (Minnesota).

Walker posted a team-high 102 tackles and an average of 5.54 solo tackles per game in 2024, the fifth-best mark in the NFL among players with 10-plus starts. Duggan helped Cooper earn PFWA All-Rookie honors in 2024 and was the only NFL player that season to record at least 75 tackles (77), 13 tackles for loss (13), 3.5 sacks, an interception, a forced fumble and two fumble recoveries. He became the only rookie since 2000 to reach those marks and posted the most tackles for loss by a Green Bay rookie since linebacker Clay Matthews had 17 in 2009.

Prior to his time in Green Bay, Duggan spent nine seasons coaching at the collegiate level. He worked under Hafley at Boston College from 2020 to 2023, serving as the linebackers coach for three seasons (2020–22) before adding co-defensive coordinator duties in 2023.

Duggan helped lead the Eagles to bowl eligibility in three of his four seasons, highlighted by a win over No. 17 SMU in the Wasabi Fenway Bowl to close the 2023 campaign. That year, he worked with linebacker Vinny DePalma, who earned third-team All-Atlantic Coast Conference honors after leading the team and ranking eighth in the ACC with a career-high 93 tackles (41 solo).

In 2022, the Eagles secured their first win over an AP-ranked opponent since 2014, when they upset No. 16 North Carolina State on the road. DePalma received All-ACC honorable mention that year under Duggan's guidance after pacing the team with 87 tackles (49 solo).

In 2021, Duggan's linebackers unit helped Boston College also post top-30 national marks in total defense (28th, 344.3 yards per game), opponent red-zone scoring percentage (30th, 76.9), first downs allowed (t-13th, 222) and third-down defense (25th, 34.5%).

In his first year at Boston College in 2020, Duggan worked with linebacker Isaiah McDuffie, whom he later coached again in Green Bay. That season, McDuffie ranked second in the conference and fifth nationally with a career-high 107 tackles (54 solo), earning second-team All-ACC honors. The Eagles improved 52 spots in the national rankings in total defense, finishing 73rd in 2020 after ranking 125th  in 2019, and allowed nearly 62 fewer yards per game than the previous year (416.8 in 2020, 478.7 in 2019).

Duggan spent the 2019 season as a graduate assistant at Ohio State, where he helped the Buckeyes field the top defense in college football. Ohio State led the nation in yards allowed per play (4.13), total defense (259.7 yards allowed per game), passing defense (156.0) and sacks (54.0), and ranked fourth in scoring defense (13.7 points allowed per game).

In 2018, Duggan coached linebackers at UMass, where he guided linebacker Bryton Barr to Eastern College Athletic Conference Defensive Player of the Year honors. Prior to UMass, Duggan spent 2016–17 in the same role at Hawai'i, where he coached linebacker Jahlani Tavai to All-Mountain West honors in 2016 and linebacker Jerrol Garcia-Williams, who went on to play 11 games as a rookie with Denver in 2017.

Duggan began his coaching career in 2015 as a defensive graduate assistant at his alma mater, Boston College. He was part of a staff that helped the Eagles lead the nation in total defense (254.3 yards allowed per game), while ranking second in rushing defense (83.2) and fourth in scoring defense (15.3 points allowed per game).

Duggan played linebacker at Boston College (2011-14), where he appeared in 45 career games and was voted a team captain as a senior in 2014. He played in 11 games with four starts in 2014, posting 36 tackles (18 solo) for a BC defense that ranked No. 2 in the nation in rushing defense (94.5 yards allowed per game).

A Cincinnati, Ohio, native, Duggan earned his bachelor's degree in marketing and operations management from Boston College in 2014. Duggan and his wife, Patrice, have one daughter, Colbie.