Arizona Cardinals running back David Johnson walks off the field with medical staff for X-rays against the Detroit Lions. (Jose Juarez/AP)

Arizona Cardinals running back David Johnson left Sunday’s game against the Detroit Lions during the second half on Sunday with a wrist injury. Johnson was placed on injured reserve Tuesday and is expected to miss two to three months after undergoing surgery to repair a dislocated wrist, per ESPN’s Adam Schefter.

The loss could be catastrophic. Johnson touched the football 373 times last season, the most by any player since Johnson was drafted in the third round of the 2015 NFL draft, and he produced a league-leading 2,118 total yards from scrimmage and 20 touchdowns last season, earning him a Pro Bowl nod and the No. 12 spot on the NFL’s list of Top 100 players in 2017. Defenses tried to stop him, but he averaged 4.0 yards per carry with 10 rushing touchdowns against eight or more defenders in the box. No running back had more broken tackles on passing plays (27) than Johnson did last season, per the game charters at Pro Football Focus.

It’s always a huge blow to lose a top player,” Coach Coach Bruce Arian told Darren Urban of azcardinals.com. “But it’s not the end of the world. It’s an opportunity for someone to step up. David Johnson became David Johnson because of somebody’s injury.”

It might be a big opportunity for another player, but it also might be the end of Arizona’s playoff hopes.

Using the same data that helped construct our power rankings, before Johnson’s injury, the Cardinals were expected to go 9-7 and secure the NFC’s second wild card. Now, they are expected to finish with six or seven wins, which would not qualify them for postseason play. There is still a chance they finish the season with nine wins or more (19 percent), but it will take a herculean effort by a committee of castoffs and unproven commodities at running back to do it.

In Week 1, the team turned to Andre Ellington and Kerwynn Williams in the backfield, with Ellington playing 20 snaps — 19 on passing downs plus one other serving as a run blocker — and Williams playing nine snaps, five on rushing plays and four on passing plays.

Week 1 vs. DET (2017) Total snaps Run snaps Pass snaps Run block snaps Pass block snaps
 David Johnson 46 11 31 1 3
 Andre Ellington 20 0 19 1 0
 Kerwynn Williams 9 5 4 0 0

Ellington, a sixth-round selection by the Cardinals in 2013, had one season as a starter, 12 games in 2014, but average a career-low 2.8 yards per carry for Arizona last season, with a minus-26.8 percent Defense-adjusted Yards Above Replacement, a Football Outsiders’ metric that measures a player’s efficiency by comparing success on every single play to a league average based on situation and opponent. With rushing numbers like that it makes sense to utilize him only in the passing game — he averages 1.53 yards per route run for his career and produced 35 yards on 15 routes run in Week 1 of the 2017 season.

Williams, a seventh-round selection by the Indianapolis Colts in the 2013 NFL draft, had a career-high 53 rushing attempts in 2014 for the Cardinals, producing 246 yards. On Sunday, Williams carried the ball five times for just 10 yards plus a two-yard catch, although he did punch in a touchdown from the three-yard line.

It’s good to see the Cardinals playing to the strengths of Ellington and Williams, but they obviously felt something was lacking: They signed running back D.J. Foster from the New England Patriots practice squad and brought back Chris Johnson, released by the Cardinals during the final round of roster cuts this year.

Foster, an undrafted free agent, appeared in three games for New England in 2016, producing 24 yards on seven carries with one two-yard catch out of the backfield. Johnson will turn 32 at the end of September and played just four games for the Cardinals last season.

Not exactly an awe-inspiring group of backs to strike fear into the hearts of opposing defenses, especially the ones waiting for Arizona this season.

According to Sharp Football Stats, the Cardinals play nine defenses that ranked at least 13th or better in terms of defending the run. Their overall strength of schedule in terms of rush defense is the sixth-toughest for the next 15 weeks of the season.


Weeks 2 to 17 of the 2017 regular season (sharpfootballstats.com)

The more likely situation is quarterback Carson Palmer has to shoulder more of the workload, which isn’t ideal either. The 38-year-old quarterback was adept at converting his short and intermediate throws (14 yards or less) last season but struggled with the deep ball, completing 50 of 129 passes (39 percent) traveling 15 or more yards in the air, with a 6-to-8 touchdown-to-interception ratio. Both marks are well below an average quarterback.

Pases traveling 15 or more yards Comp% Yd/Att TD/Int Passer rating
 Carson Palmer (2016) 39% 9.29 0.75 62.8
NFL average (2016) 43% 11.7 1.46 90.1

On Sunday against the Detroit Lions he threw three interceptions — one on a deep throw — and posted a 29.2 passer rating on passes that took 2.6 seconds or more to attempt. An incomplete pass produces a passer rating of 39.6, so the Cardinals would have been better off if Palmer just threw the ball away on those 23 drop backs rather than attempt a pass.

I am concerned about Carson Palmer,” former Arizona quarterback Steve Beuerlein said on Monday. “You look at what happened [against the Lions on Sunday]. They had a 17-9 lead, late in the third quarter. He’s up there in years, we know that. I don’t think he’s the same quarterback who can carry a team on his shoulders like he once was.”

If the Cardinals want to reach the playoffs, he may have to.

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