Sean Duggan

Quick Facts

Role: Defensive Coordinator
Team: Miami Dolphins (MIA)
Current holder: Sean Duggan
Coaching tree: Packers/Hafley branch; see Coaching Trees

Background

Duggan spent one season as a co-DC in college (Boston College, 2023) and just two years in the NFL — a Packers defensive assistant in 2024, then promoted to linebackers coach in 2025. Last season he helped Quay Walker, Edgerrin Cooper, and Isaiah McDuffie combine for 338 tackles. Familiar with new HC Hafley from their Packers time. Play-calling stays with Hafley, so Duggan manages the rest.

Scheme and Tendencies

Duggan manages the Dolphins' scheme under Hafley, who retains play-calling authority. The base is nominally 4-3 but highly flexible—Hafley rejects rigid scheme labels, preferring to match personnel to opponent needs. Frequent use of nickel and big-nickel packages (safeties playing linebacker/nickel positions); "jersey numbers and people" dictate the front seven, with interior tackles (Sieler, Phillips, Grant) and edge rushers (Robinson, Uche) rotating based on personnel fit. Interior defensive line is a focus area—Hafley wants Sieler and Phillips to assert dominance at the line of scrimmage. Defensive end remains a question mark with a mix of first-round prospect Robinson and veteran acquisitions (Ojabo, Uche) in their respective phases. Inside linebacker trio (Brooks, Dodson, Rodriguez) can see simultaneous snaps, with coverage responsibilities split based on package. Secondary is inexperienced; cornerback Chris Johnson and hybrid LB/nickel Kyle Louis are key development pieces. Zone-heavy base with cloud coverage on secondary; blitz rate expected to remain conservative in 2026 given personnel limitations (per Here's what Dolphins fans can expect from Jeff Hafley's defense | Countdown to camp).

Recent News

2026-08-28 — How every 2026 NFL draft pick has looked in the preseason (How every 2026 NFL draft pick has looked in the preseason)
2026-03-27 — AFC Coaching Changes: How the 9 New Defensive Coordinators Will Impact IDP Leagues for... (AFC Coaching Changes: How the 9 New Defensive Coordinators Will Impact IDP Leagues for...)
2026-03-24 — 2026 NFL Draft: Expectations for seven teams with completely new coaching staffs (2026 NFL Draft: Expectations for seven teams with completely new coaching staffs)
2026-02-20 — 2026 NFL Coaching/GM Tracker: Rams Find Their Offensive Coordinator In-House (2026 NFL Coaching/GM Tracker: Rams Find Their Offensive Coordinator In-House)
2026-08-19 — 2026 Fantasy Football Trends: Fantasy Impact of Coaching & Personnel Changes in the... (2026 Fantasy Football Trends: Fantasy Impact of Coaching & Personnel Changes in the...)
2026-06-22 — Early 2026 Fantasy Football IDP Players To Target In the First Round (Early 2026 Fantasy Football IDP Players To Target In the First Round)
2026-03-24 — Draft expectations for 7 teams with new coaching staffs (Draft expectations for 7 teams with new coaching staffs)
2026-07-30 — Miami Dolphins | Jeff Hafley Fantasy Football Scheme Fit (Miami Dolphins | Jeff Hafley Fantasy Football Scheme Fit)
2026-05-21 — 2026 Projected IDP Depth Charts (2026 Projected IDP Depth Charts)
2026-03-24 — Official Site of the National Football League (Official Site of the National Football League)

Sources

Dolphins reboot with Hafley HC, Slowik OC, Duggan DC for 2026 draft
Full list of 2026 NFL coordinator grades from CBS Sports