In the final hours before the NFL Trade Deadline, it was revealed that the Miami Dolphins would be losing defensive lineman Zach Sieler for the remainder of the season with ruptured biceps that occurred in Miami’s Week 9 matchup with the Detroit Lions.

Sieler has been the Dolphins’ most consistent defender in 2026, and for a unit that has come alive over the last month, this injury means having to adapt to life without Miami’s longest-tenured player, which will certainly be difficult given his diverse skill set.

How It Impacts the Dolphins Pass Rush

Sieler’s impact on Miami’s pass rush cannot be overstated. Along with being their most frequent one-on-one winner on the interior, Sieler has mastered stunts and games. His timing and hand placement are stellar when occupying blocks and allowing the likes of Josh Uche and Chop Robinson to get to the backfield unscathed.

Without Sieler, the cohesiveness and aggression that this group has evolved into over the last couple of weeks takes a significant hit. Utilizing his ability on pick stunts was Miami’s primary method of generating pressure, and while Uche and Robinson have certainly showcased their isolation skills, Jeff Hafley no longer has an “easy button” on crucial downs. Miami will certainly keep these looks in their gameplan, but with Sieler carrying so much of that workload prior to this injury, it’s unknown how steep the drop off in effectiveness will be.

How It Impacts the Dolphins Run Defense

Sieler’s run-game skill set is also unique. As Miami's lightest and most twitchy rotational player on the interior, he’s often tasked with shooting a gap, while Jordan Phillips and/or Kenneth Grant absorb and attempt to deconstruct blocks. His ability to quickly disrupt while maintaining strong positioning often leads to runs being bounced away from him and where other defenders can rally and tackle.

Replicating this is where I think head coach Jeff Hafley can be creative. Rather than simply using Phillips or Grant, both of whom have worked better clogging lanes and occupying double teams, it wouldn’t be shocking to see one of Miami’s edges see more work slanting to the inside, while Jordyn Brooks or Willie Gay Jr., who are at their best against physicality, play a strong-side linebacker role as de facto edge defenders on run downs. Gay already occupies a similar space when on the field, and moving him to a more run-first role may eliminate some of the struggles he has in pass coverage.

Down the stretch of the season, rookie Trey Moore may also have an impact stepping into that hybrid role. Moore has spent the entirety of the 2026 season on injured reserve with an ankle injury, but appeared to be a starter prior to going down.

Next Man Up

Potentially the biggest impact of losing Sieler isn't schematic, but rather what he provides as a leader among one of the youngest positions in the league. Sieler, a team captain who has been with Miami since 2019, has been a part of three different regimes, and had adopted the role of mentor to Kenneth Grant, Jordan Phillips and Zeek Biggers, all of whom were selected in the 2025 draft.

Now, the pressure is on Miami’s three young interior pieces to not only fill in the gap Sieler left, but also prove that they’re foundational pieces of a rebuild under a different coach than the one that drafted them. With the aforementioned Grant returning from injury in Week 5, the puzzle pieces appeared to be falling into place over the last month, but now this unproven unit must operate without its key cog.

Miami’s defense, which had prioritized simply getting to a point where everyone could play their 1/11th effectively, now needs its youngest group to pick up extra slack, and the question of whether they can could be one of the early turning points of the Jeff Hafley era.