SANTA CLARA, Calif. – Dissecting, each week, what needs to be fixed on their respective sides of the ball is something that Patrick Peterson and Larry Fitzgerald have handled for many years now.

They both have been around long enough to have played for some very good teams and some teams that have struggled mightily.

Neither has been on a team still seeking its first victory in October, which is where the Cardinals find themselves as they play the 49ers (1-3) Sunday at Levi's Stadium.

"It's been extremely tough," Peterson said. "You always want to win and do whatever you can to put your team in the best position possible. There is nothing like winning. I don't care how you cut it – there's nothing like winning."

"This doesn't feel nearly as bad as starting 4-0 and dropping eight in a row," Fitzgerald said, recalling the Cardinals' rough 2012 season. "There have always been worse scenarios. Obviously, we are frustrated with the way we have performed. We know we have to play better."

The Cardinals have played better the last two games. Losing by two to the Bears and three to the Seahawks doesn't improve the won-lost margin, but it does mark some steps forward, especially in light of facing a 49ers team that has been beat up by injury – including the season-ending ACL tear for starting quarterback Jimmy Garoppolo.

The Cardinals underwent their own quarterback change last week, with rookie Josh Rosen taking over behind center. It went well – he didn't turn the ball over, and his 180 yards passing would have been significantly higher without multiple drops – but Rosen wasn't making any predictions for start No. 2.

"I have no expectations or ever play with any," Rosen said. "I just want to win a game. I don't even care if I play worse, as long as we win."

Running back David Johnson also had a season-high 25 touches last week, something that can help Rosen. But the 49ers now have a game to scout Rosen upon, and the Cardinals will do what they can to prevent too much of the inevitable rookie quarterback ups-and-downs.

49ers coach Kyle Shanahan said that Rosen's lack of experience could give San Francisco a chance to confuse Rosen, although Rosen said the Cardinals are expecting some wrinkles and will be ready to adjust to whatever might be seen.

It'll also help Rosen if the Cardinals' defense can find a way to crack down on a solid (sixth in the league) San Francisco running game, which the 49ers want to use to help backup quarterback C.J. Beathard. The 49ers also have three starting offensive linemen questionable to play because of injuries.

That's certainly not where the 49ers expected to be at this point, not with the high hopes behind the emerging Garoppolo.

"That takes a toll," Shanahan said. "Everyone's got to step it up."

The message is similar to the one Wilks has had for a month. Wilks said the defense has to clean up its tackling – GM Steve Keim said this week the Cardinals missed 22 tackles against the Seahawks, allowing 167 yards after contact – and with Rosen, "I think our offense is getting ready to flourish."

Fitzgerald holds optimism this week, but then again, he has optimism every week. It's the only approach to take.

"I'm a creature of habit," Fitzgerald said. "I've been doing this since I was 6 years old. I don't look at it any different. You prepare the same way every single week. There are some good weeks, and some bad weeks. That's the way it goes."