The team's feature back and consensus No. 1 overall pick in all fantasy football formats suffered a severe wrist injury against the Lions and is slated to miss "an extended period of time" according to NFL Network's Ian Rapoport. Johnson led the entire NFL in yards from scrimmage (2,118) and scrimmage touchdowns (20) in 2016, which ranked him as the highest-scoring fantasy running back last year with 327.80 fantasy points.
According to Rapoport, Cardinals' coach Bruce Arians said that Johnson has been diagnosed with a dislocated wrist, is a candidate for surgery, and will likely land on the injured reserve list. Per Arians, the team will get a second opinion before making a final decision but either way, it's an extremely unfortunate development both for Arizona's offense and for fantasy managers who roster Johnson as their RB1. We'll be keeping a close eye on any further developments regarding Johnson's prognosis, but for now, we must figure out how to move forward.
Williams has been with the Cardinals since 2014, a season in which he posted a career-high 53 carries for 246 yards. He posted above-average speed and middle-of-the pack agility measurables at the 2013 combine but possesses minimal versatility compared to his injured teammate. Still, he's likely first in line for carries in the short-term.
Andre Ellington, who has been an Arizona Cardinal his entire career, is also a potential pass-catching option since Williams has maxed out at two receptions as his high in any given season. Ellington's size, 5-foot-9, 199 lbs, makes him vulnerable to durability concerns, so he's not a candidate to handle a bell-cow type workload but could see some looks as a receiver.
We can't forget that the team cut veteran and former backup to Johnson, Chris Johnson, during the preseason. The aging CJ2k had an underwhelming 3.2 yards per carry average on 10 preseason rush attempts. But even at his advanced age, 31, he knows the Cardinals offense better than anyone else the team would sign off the street making him a potential re-sign option. Chris Johnson put up 814 rush yards on 196 carries back in 2015, before then-rookie David Johnson took the reins. CJ2k remains a free agent for now, but that could change soon.
The order you should attack these Cardinals backs on the waiver wire is the same way they're listed in this article. If the team does sign Chris Johnson, he'd probably receive a higher workload than the others, but you have to ask yourself if you're in the position to risk a waiver claim or FAAB budget on a 31-year-old free agent at the moment.
Not a single running back from the waiver wire will be able to provide the value that David Johnson gave your roster, but there are a few other upside options like Tarik Cohen, Javorius Allen, Marlon Mack and Chris Carson who are available as weekly flex plays. More details on some of these backs can be found in Alex Gelhar's waiver wire write up here.