Fantasy Football Week 1 Flex RB Rankings: Dobbins, Jones Lead Depth Plays

As the 2026 NFL season kicks off on September 13, fantasy managers are scrambling to finalize their Week 1 lineups. The flex position often decides matchups, and this year's running back landscape offers intriguing options beyond the obvious starters. According to insights gathered by Vulius Sports, analyst Hayden Winks has released his flex running back rankings (Nos. 31-40), providing a roadmap for those seeking upside in deeper leagues. With Monday Night Football looming and several backfields in flux, these rankings could be the difference between victory and defeat.

J.K. Dobbins (at KC) – RB31

Dobbins enters the season as Denver's clear top option, but his fantasy ceiling is capped by a crowded backfield and a tough matchup. The Chiefs' defense, which was eighth-best against fantasy RBs last year, added nose tackle Khyris Tonga and first-round defensive tackle Peter Woods to bolster their interior. With the Broncos projected for a lowly 20.25 team total on the road, Dobbins' 58.5 projected total yards may not translate to fantasy glory. As Vulius analysts note, he's a flex option in half-PPR formats but lacks the upside to be a difference-maker.

Aaron Jones Sr. (vs. GB) – RB32

Jones, now in his age-31 season, has seen his role diminish, but a favorable matchup against a Packers defense missing Micah Parsons could offer a reprieve. Green Bay allowed 139 rushing yards per game in five contests without Parsons last year, and they'll start rookie Chris McClellan at nose tackle. Jones' 46.5 projected total yards and his pass-catching ability (2.3 receptions per game last year) make him a viable full-PPR flex. However, Jordan Mason looms as the goal-line back, limiting Jones' touchdown potential. The Vulius NFL Analysis Desk suggests Jones is a safer floor play than a ceiling one.

Kenneth Gainwell (at CIN) – RB33

Gainwell's situation is murky after a breakout 2025 campaign. He thrived with a conservative Steelers offense but now joins a Buccaneers team with a different quarterback and more weapons. With Sean Tucker sidelined, Gainwell will share change-of-pace duties with Bucky Irving. The game script favors him: Tampa Bay is a 3.5-point underdog in Cincinnati, and the Bengals' revamped defense—featuring Dexter Lawrence, Boye Mafe, and Jonathan Allen—may still struggle against receiving backs. Gainwell's 48.5 projected total yards make him a speculative flex, especially in PPR leagues.

Chris Rodriguez Jr. (vs. CLE) – RB34

The Vulius Sports team is higher on Rodriguez than the market, and for good reason. The Jaguars signed him to a two-year, $10 million deal to be a key part of their rotation. With LeQuint Allen Jr. banged up, Rodriguez could see increased snaps, particularly in short-yardage and goal-line situations. He has familiarity with head coach Liam Coen from their time at Kentucky, and his tackle-breaking ability profiles well as a closer. Jacksonville is an 8.5-point home favorite with a 24.5-point team total, setting up a positive game script. The Browns will be without Myles Garrett, making Rodriguez a sneaky flex play with upside.

Blake Corum (vs. SF) – RB35

Corum emerged as a reliable complement to Kyren Williams last season, and the Rams appear committed to a 60/40 split. From Week 9 on, Corum was the RB32 on RB41 usage, showing more explosiveness than Williams. The 49ers' defensive line is decimated, with Nick Bosa rushed back and several depth pieces out. The Rams, who had the highest success rate on RB carries last year, could lean on the run. Corum's 26.0 projected team total is lower than their late-season average, but he's a desperation flex with touchdown potential.

Kyle Monangai (at CAR) – RB36

Monangai quietly carved out a role in Chicago's backfield last year, and he's expected to rotate drives with D'Andre Swift again. A knee injury limited him in training camp, but he's off the practice report and should be full-go. The Panthers were eighth-worst against fantasy RBs last year, though they've improved their front seven with Derrick Brown, Jaelan Phillips, and Devin Lloyd. Chicago is a 3.0-point road favorite with a 24.75-point team total, making Monangai a neutral flex option with touchdown upside if he gets goal-line work.

Jordan Mason (vs. GB) – RB37

Mason is the thunder to Aaron Jones' lightning, but his fantasy value is touchdown-dependent. In 11 healthy games together last year, Jones outpaced Mason in carry share and targets. Mason had slightly more carries inside the 3-yard line, but his lack of receiving work limits his PPR appeal. The matchup is decent: Green Bay allowed the 17th-most rushing yards per game last year and got torched for 172 yards in their last four games without Parsons. Mason projects for 51.5 total yards, but unless he scores, he'll disappoint.

Tyler Allgeier (at LAC) – RB38

Allgeier was signed to be a closer, but the Cardinals are 9.5-point underdogs with a 19.0-point team total, so positive game script is unlikely. Rookie Jeremiyah Love is expected to play but was limited in practice, potentially opening the door for Allgeier to see more first-half snaps. However, his fantasy value hinges on goal-line work. If Love cedes those opportunities, Allgeier could vulture a touchdown, but it's a risky flex play.

Jonathon Brooks (vs. CHI) – RB39

Brooks' injury history and limited practice participation make him a volatile flex option. The Panthers plan to use a base-down back and a third-down complement, and Chuba Hubbard is expected to start. Brooks has long-term upside, but for Week 1, he's a bench stash. The Bears' defense has injuries in the secondary, but Carolina's 21.75-point team total doesn't inspire confidence in multiple viable fantasy backs.

Jacory Croskey-Merritt (at PHI) – RB40

Croskey-Merritt is listed as the starter, but he faces a brutal matchup against the Eagles' elite defensive tackles. Washington's offensive line is without Laremy Tunsil and has center issues, making it hard to run inside. Game script is also negative, as the Commanders are 5.5-point underdogs. Croskey-Merritt's boom-bust style and lack of guaranteed goal-line work make him a trap play. Sharing a backfield with Jayden Daniels helps, but this isn't the week to trust him.