Adrian Peterson once tormented the Redskins, his newest employer. (Toni L. Sandys/The Washington Post)

Three healthy running backs. That’s all the Washington Redskins had during their last two practices before deciding to sign future Hall of Famer Adrian Peterson on Monday.

The backfield has been in flux since second-round pick Derrius Guice was lost for the season with an anterior cruciate ligament tear in his left knee, suffered during Washington’s preseason opener. The situation turned dire when Samaje Perine and Byron Marshall were injured in the second preseason game. The organization brought in Peterson, Jamaal Charles and Orleans Darkwa for workouts before deciding to sign the 2012 NFL MVP.

The addition of Peterson makes projecting the 53-man roster even more difficult, assuming the 33-year-old will be on the team when the regular season begins. (It’s unlikely he would have signed in Washington just to be a camp body.) The seven-time Pro Bowl back ran for 529 yards in 10 games last season, and his last standout season was a 1,485-yard, 11-touchdown effort with the Minnesota Vikings in 2015. He was the biggest name available in free agency, regardless of position, and ranks 12th in league history with 12,276 rushing yards. Peterson, however, dealt with injuries in both 2016 and 2017.

Coach Jay Gruden said Sunday the team was more concerned with aligning itself for the season opener Sept. 9 against the Arizona Cardinals than bringing in a new back, but that changed fairly quickly. Practices and two more preseason games would have been difficult with just three backs, and the time frame for the return of Perine (ankle) and Marshall (lower leg) remains unclear.

The team will likely keep four running backs, and the competition will now kick back up, assuming Peterson, Chris Thompson and Rob Kelley are safe bets.

Below is our second projection for the team’s final 53-man roster.

Quarterbacks (3): Alex SmithColt McCoy, Kevin Hogan

Smith and McCoy are locks. The question is, will Gruden keep a third quarterback? Hogan hasn’t lit the world on fire, but he has picked up the offense. McCoy’s contract extension through 2019 didn’t help Hogan’s chances, but McCoy still wants a shot to be a starter somewhere and Hogan could replace him as Smith’s backup in 2020.

Running backs (4): Chris Thompson, Rob Kelley, Samaje Perine, Adrian Peterson

The injury situation, combined with Peterson’s signing, leaves two probable spots for three players.  Thompson, Kelley and Peterson should be in. Perine is likely next in line, as long as his injury doesn’t take a strange turn, but it’s not expected to be a long-term ailment. Kapri Bibbs was in a battle with Byron Marshall, but the addition of Peterson puts Bibbs on the bubble.

Wide receivers (6): Paul Richardson, Josh Doctson, Jamison Crowder, Trey Quinn, Maurice Harris, Cam Sims

Richardson, Doctson and Crowder are starters while Quinn — the final pick in the 2018 draft — has shown great hands in the slot. Harris has shined in both practices and preseason games and, after the season-ending injury to Robert Davis, should be in. This decision comes down to Cam Sims or Brian Quick. Sims, an undrafted college free agent, has five catches for a team-high 131 yards in preseason. He had a drop that turned into an interception against the Jets, but he bounced back spectacularly, and also had an acrobatic touchdown grab called back by penalty. The problem with keeping Quinn, Harris and Sims is that Harris’s 12 career receptions would represent the most experience in the room after the starters. Quick has 111 catches in six NFL seasons.

Tight ends (3): Jordan ReedVernon DavisJeremy Sprinkle

Reed and Davis are in, and Sprinkle has looked like the best pass-catching option of the remaining tight ends. Manasseh Garner is out for the season, so Matt Flanagan would be the other possibility. He is a better blocking option than Sprinkle, if the staff decides that’s a bigger priority behind strong receivers in Reed and Davis.

Offensive line (8): Tackles Trent WilliamsMorgan MosesTy Nsekhe and Geron Christian; guards Brandon ScherffShawn Lauvao and Tony Bergstrom; center Chase Roullier

This projection has swapped Tyler Catalina for Bergstrom, since Gruden wants a backup center who can also play guard. Bergstrom has gotten the lion’s share of the snaps at backup center. The other seven are penciled in barring injuries.

Defensive line (7): Jonathan Allen, Daron Payne, Tim Settle, Matt IoannidisZiggy HoodStacy McGeeAnthony Lanier

Stacy McGee has been on the physically unable to perform list, but he will make the roster if the injury isn’t an issue. Phil Taylor would be first man out, or last man in without McGee.

Linebackers (9): Ryan Kerrigan, Zach Brown, Mason FosterPreston SmithRyan AndersonPernell McPhee, Shaun Dion Hamilton, Martrell Spaight, Pete Robertson

Spaight and Robertson are the newcomers to the list, but both have earned it with their recent play. Spaight has been consistent, and Gruden has raved about Robertson. This is another position that could make do with one fewer body than in 2017 to make the numbers work. Josh Harvey-Clemons started the summer with the first team when Brown didn’t attend OTAs, but has dropped back in the pack recently and has also dealt with a hamstring issue. He projects as the 10th linebacker.

Cornerback (6): Josh NormanQuinton DunbarFabian MoreauJoshua Holsey, Greg Stroman, Danny Johnson

The Redskins committed to a youth movement at cornerback when they released Orlando Scandrick. Johnson has been the biggest surprise in the secondary as an undrafted college free agent, but he has likely played himself onto the roster. Gruden said Holsey remains in the team’s plans, though he missed training camp after a table fell on his foot. Stroman’s special teams skills give him an edge, and Adonis Alexander remains on the bubble due to the upside in his 6-foot-3, 197-pound frame.

Safeties (4): D.J. SwearingerDeshazor EverettMontae Nicholson, Troy Apke

These four have easily been the top four safeties. Numbers could prevent Quin Blanding from making the cut.

Special teams (3): P Tress Way, K Dustin Hopkins, long snapper Nick Sundberg

The trio should have a fourth season together.

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