Cardinals wide receiver John Brown scored a touchdown against the Panthers but still wasn't back to his usual self.

Many within the Cardinals' organization have a soft spot for wideout John Brown, the underdog who exploded onto the NFL scene two years ago and followed it up with a 1,000-yard receiving season in 2015.

It's been hard for them to watch him struggle this season due to a concussion in training camp and sickle cell trait complications of late. So coach Bruce Arians was excited to share the news Friday that Brown, who has just 28 catches for 350 yards and a touchdown this season, has turned the corner and gotten back to his old self.

"The last two days, he looked like John Brown," Arians said. "He was smiling, laughing, running fast, doing all the things that John Brown looks like. It's really refreshing to see it on the field. Knock on wood there's no relapse, but it looks like he's got everything under control physically, which has allowed him mentally, I think, to come back and be himself."

Brown has only missed one game this season but has been quiet in several others. He said the fatigue from the sickle cell trait caused him frustration until he learned how to combat it.

"It was tough not able to help the team how I wanted to," Brown said. "Looking at myself on film, I wasn't the same. I wasn't playing fast. It's out of my head now. I feel good."

Arians said J.J. Nelson will be the No. 2 receiver this week alongside Larry Fitzgerald, but that both Brown and Michael Floyd are healthy and will be counted upon.

"It's important to get them both going," Arians said. "We need both of them. It's obvious we missed the plays that they've made the past couple of years for our offense. And I would anticipate both of them to have really big finishes."

Floyd played sparingly last week in part because of a hamstring injury and failed to register a catch, but quarterback Carson Palmer sees a breakthrough on the horizon. Floyd has 19 receptions for 257 yards and three touchdowns this season.

"I expect this second half, Mike to have as big of a year as any receiver could," Palmer said. "I'm not down on his confidence. He's not down on confidence. I was talking to somebody (Wednesday). He had two unbelievable days of practice. I think he's going to explode in the second half and people have doubted and have said negative things about a couple individual plays. But that's not Mike. Mike is a game-changing player. Mike's going to make plays that win games for us. I don't know how many, but it's going to be a lot."

OFFENSIVE LINE CRITICAL DOWN THE STRETCH

The Cardinals' receivers need to improve, but the most crucial position group for the second half of the season may be the offensive line.

The unit had its worst game of the season last time out in Carolina, allowing eight sacks in a 30-20 loss, and will play the rest of the way without injured left tackle Jared Veldheer and right guard Evan Mathis.

Earl Watford has taken over for Mathis and now John Wetzel will take over for Veldheer. If the offensive line doesn't hold up, it will be hard to get the skill players going.

"I think how we do is always important," right tackle D.J. Humphries said. "If you don't protect the quarterback, no balls get off. If no balls get off, playmakers can't make plays. I think it all starts with us, and how physical we're playing, and how physically sound and mentally sound we are."

MATHIEU WON'T PLAY AGAINST 49ERS

Safety Tyrann Mathieu (shoulder) and cornerback Tharold Simon (ankle) have been ruled out for Sunday's game. Rookie Brandon Williams or veteran Justin Bethel is expected to play cornerback in nickel packages. Linebacker Alex Okafor (calf) is questionable.

Wide receiver Larry Fitzgerald (ankle) was limited in practice every day this week but will play.

For the 49ers, linebacker Aaron Lynch (ankle) is out. Running back Carlos Hyde (shoulder), cornerback Rashard Robinson (knee) and wide receiver Torrey Smith (back) are questionable.