A glance at the top storylines for the Cardinals-49ers game Sunday at University of Phoenix Stadium:

**Run, David, run.

The math is simple. The NFL's fourth-leading rusher versus the NFL's worst run defense really should equal big numbers – perhaps bigger than the 157 yards David Johnson gained on the ground against the 49ers earlier this season. San Francisco's defense is a mess, and that was before defensive lineman Arik Armstead went down for the season. The Cardinals might have a chance to move it through the air too – don't forget, Carson Palmer missed the first game against the Niners – but all signs point to a heavy dose of Johnson (and even, maybe, Andre Ellington?)

Seeking a repeat for Kaepernick

It was his worst game, a nightmare for Colin Kaepernick that played out at University of Phoenix Stadium last season. Two pick-6s on his first two possessions, bedlam from the crowd, and eventually a 47-7 loss. The dynamics have changed this season, obviously, starting with the fact Tyrann Mathieu – who had two interceptions that day – isn't expected to play. Kaepernick, who did not play in the two games against the Cardinals in between then and now, is also running a different offense. But the Cardinals, who are now the No. 1-ranked defense overall and fifth in scoring defense, have a chance to squeeze the life out of a reeling team.

Watching Wetzel

Jared Veldheer is out, and that's something the Cardinals haven't had to say at all since Veldheer actually became a Cardinal. It's an unsettling feeling to be missing your high-quality left tackle in a league where you really need a high-quality left tackle. Now we'll see what John Wetzel, Veldheer's replacement, can do. It isn't being unfair to Wetzel to wonder, since he's played very little left tackle and he isn't as good as Veldheer – because otherwise, he'd be starting. Wetzel has held up pretty well in spot replacement duty both for Veldheer and Mike Iupati, but having the job permanently and being steady in that role is something different. Wetzel's bigger test comes next week against the Vikings, but that won't take the spotlight away this week.

An explosion of Floyd?

Palmer said he thinks wide receiver Michael Floyd will have a big second half of the season. This would be a good place to start, with the Niners struggling on defense. Palmer was optimistic about Floyd's solid practices this week. Having him get loose against a San Francisco secondary that was beat up by Drew Brees and the Saints last week might be the jumping-off point Floyd needs.

Fulfill the expectations

The Cardinals are still trying to figure out how good they really are – many statistics and metrics show they are playoff-worthy in the NFC, but the record does not – but it's safe to say the 49ers are not good. This is a game the Cardinals should control, at home. They need to show it. Style points mean nothing in the end, but this is one where the Cards could use a win with those style points. If for no other reason than to build confidence going into a tough two-game stretch of schedule on the road at Minnesota and Atlanta. 

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