David Johnson said he has returned to the "prove-it phase" after struggling in his return to the field last week in Tampa.
The running back reiterated Friday injury issues aren't to blame after he gained just 2 yards on five carries and fumbled away his lone reception before being benched in the fourth quarter of the loss to the Buccaneers.
"Just a bad game, just a bad game," Johnson said. "Not everyone is perfect. Biggest thing is what you do after a bad game."
Kliff Kingsbury said earlier this week Johnson's benching wouldn't carry over, and the coach added Johnson had responded well in practice this week.
"I'm proud of his effort and his focus," Kingsbury said. "I like where his head is at."
Kenyan Drake, for whom the Cardinals traded just before the first meeting with the 49ers, dominated in that game with 110 yards on just 15 carries. Johnson was inactive for that game. Kingsbury said the running back situation will be "by committee," and that the starter does not mean a lot.
"In our offense, I don't think so," Kingsbury said. "We change personnel groups a ton. I'm not going to screw Larry's streak up. Put that out there for Mr. (Michael) Bidwill.
"But other than that, our guys know we are going to put certain personnel groups out based on certain plays. It has nothing to do with if they are a starter or not."
Johnson has had multiple good games this season, mostly receiving. He has looked noticeably tentative at times running the ball, and he acknowledged he too often is trying to "make too many reads" on a play instead of just running.
Because Johnson didn't play in the first 49ers matchup, Drake essentially took all the offensive snaps. Johnson praised Drake, saying his arrival only means the Cardinals have added another weapon and that Drake has shown he is a "great player."
Johnson said his pairing this time around can only help the Cardinals and Drake, keeping both backs fresh. But that only works if Johnson can show the effectiveness he already flashed this season in making big plays against the Lions, Bengals and Falcons.
"He's the only one who can get himself out of this hole," General Manager Steve Keim said Friday morning on 98.7, Arizona's Sports Station.
Johnson insists he's ready to do that, in whatever fashion he might be deployed.
"Wherever they need me, whatever opportunities I get, I'll make the most of it," Johnson said.
JUSTIN MURRAY, TERRELL SUGGS QUESTIONABLE FOR SUNDAY
Kingsbury said right tackle Justin Murray (knee) and linebacker Terrell Suggs (hamstring/back) are both game-day decisions for the Cardinals. The decision on starting right tackle – Murray or Justin Pugh – will be decided that day as well, Kingsbury said.
Running back Chase Edmonds (hamstring) was ruled out, as was defensive lineman Jonathan Bullard (foot). Officially, fellow defensive lineman Zach Kerr (knee) is also questionable, although defensive coordinator Vance Joseph said he'd have five defensive linemen up and Kerr would be the fifth.
Cornerback Tramaine Brock (hamstring) is also questionable.
Officially doubtful for the 49ers include tight end George Kittle (knee/ankle), kicker Robbie Gould (quad) and running back Matt Breida (ankle). Tackle Joe Staley (finger) and defensive tackle D.J. Jones (groin) are out. Wide receiver Emmanuel Sanders (ribs) is questionable despite not practicing all week, and he reportedly will try to play. Also questionable are cornerback Ahkello Witherspoon (foot/quad), wide receiver Dante Pettis (back), running back Raheem Mostert (knee) and linebacker Azeez Al-Shaair (concussion).
THE THIRD-DOWN ACHILLES HEEL OF THE CARDINALS
The Cardinals might've been able to topple the then-undefeated 49ers two weeks ago had they been able to stop the Niners on any one of three third-down situations on the Niners' final clock-bleeding drive. They would've knocked off the Buccaneers last week as well had they just had another couple of third-down stops.
Instead, both games were three-point losses, and the Cardinals continue to struggle with the situation. The Cardinals have allowed 18 of 32 third-down conversions the last two games, and 12 of those conversions came when the opponent needed at least six yards – and often times more – for a first down.
"We have to win those," defensive coordinator Vance Joseph said. "We've lost the last couple of weeks probably seven to eight third-and-longs, which are hard, at first, to even get teams into. If you get teams in that (situation), you have to be at least 90 percent."
It's a mentally draining sequence, with the defense putting itself in a good position to begin with before the inability to get off the field. Cornerback Patrick Peterson said Joseph is making the correct decisions on every down, including third.
"It falls back on us as players to go back out there and execute the call the coaches give us," Peterson said. "It's been nine times out of 10 (that) Coach puts us in the right call and us as players – myself included – haven't been executing. It's going to come down to winning those one-on-one matchups, executing what the coach calls, and having that extreme focus for 60 minutes."
Images from practice at the Dignity Health Arizona Cardinals Training Center