Dolphins adjust their practice squad, adding edge Amari Gainer and releasing Keith Cooper Jr.

The Miami Dolphins announced a pair of practice squad moves on Oct. 8, signing edge Amari Gainer to their practice squad and releasing defensive lineman Keith Cooper Jr. from the practice squad. The transactions report a continued emphasis on flexible front-seven depth as Miami manages weekly roster needs.

Cooper Jr. had a unique two-step run with the Dolphins this season. He joined Miami on Jan. 9, 2026, and then spent the first three weeks of the season on the active roster before being returned to the practice squad. According to the Dolphins, he has appeared in four career games across two teams, with one tackle logged during his time in those appearances.

The release also places a spotlight on Cooper Jr.’s broader journey through the NFL. The Dolphins said he entered the league as an undrafted college free agent with Detroit in 2025, spending time on practice squads with the Lions and the Browns before landing in Miami.

Cooper Jr.’s professional path is rooted in a defined college production profile. The Dolphins reported that he finished his collegiate career at Houston, where he started 12 games in 2024 and recorded 46 tackles (25 solo), 3.5 sacks, and 8.5 tackles for loss. They also noted his ball-hawking contributions, including two passes defensed and one fumble recovery.

Before Houston, Cooper Jr. transferred to the program from Tulane after the 2023 season. Miami’s release states that during his three seasons with the Green Wave (2021-23), he appeared in 39 career games with 15 starts and produced 73 tackles (37 solo), 10.5 sacks, 16 tackles for loss, five passes defensed, and one forced fumble.

For Gainer, the Dolphins’ announcement was more limited in detail. The team identified him simply as an edge defender and said they signed him to the practice squad, adding another prospect for Miami’s offseason-plus development pipeline and weekly scout-team preparation.

Practice squad turnover is often less about one game and more about what a team wants its coaching staff to evaluate in practice. Miami’s move with Cooper Jr., after active-roster time and a return to the practice squad, indicates the team is shifting priorities in its defensive personnel look while bringing in Gainer for additional runway.

The immediate next step for the Dolphins is straightforward in terms of operations, the team will integrate Gainer into their weekly practice plan and adjust the defensive line rotation accordingly. For Cooper Jr., the release means he will seek his next opportunity on another roster or practice squad, while Miami moves forward with its current depth-building approach.

As the season moves deeper, these roster shuffles can matter in subtle ways, especially for front-seven units that rely on depth to handle injuries, matchups, and matchup-specific game planning. The Dolphins’ Oct. 8 transactions keep that option set active, and the coming weeks will determine whether Gainer becomes part of Miami’s longer runway or remains a short-cycle practice option.