One week, Iowa looks like it can't be stopped. Then, the Hawkeyes look like they can't stop anyone.

The inconsistency is as puzzling as it troubling.

The Hawkeyes (6-3, 3-2 Big Ten) will head to Illinois (4-5, 1-4) on Saturday in hopes of halting one of the most up-and-down stretches they've experienced in 16 years under coach Kirk Ferentz.

Iowa sandwiched a 41-point victory over Northwestern in between a 38-31 loss at Maryland and last weekend's 51-14 blowout loss at Minnesota.

The Hawkeyes still have a slim shot at winning the Big Ten West. But they have a lot of issues to overcome before they can think about overtaking Minnesota, Wisconsin or Nebraska.

"You need 11 guys doing the same thing, doing the right thing on every play. Maybe we're not getting as much of that. It's on all of us," running back Mark Weisman said.

The Hawkeyes have been surprisingly easy to run on this season. Tackles Carl Davis and Louis Trinca-Pasat are among the most talented and physical linemen in the Big Ten. But opponents are often running around those two and successfully attacking Iowa's young linebackers.

Quinton Alston is the only senior linebacker on Iowa's depth chart — and he spent his first three seasons as a backup.

"We're not as good at linebacker as we were a year ago. But we knew that in August," Ferentz said. "We still have an opportunity to play good team defense. We have played good defense at times. It's just a matter of being more consistent."

Minnesota used a variety of jet sweeps and zone-read plays in running for 291 yards, the third time in four games in which Iowa allowed at least 200 yards on the ground. The Hawkeyes are 11th in the Big Ten in rushing defense in league games at 201.6 yards — nearly twice what league-leading Wisconsin is giving up.

The return of sophomore linebacker Reggie Spearman from a two-game suspension should help. But the Hawkeyes still need to show improvement in stopping outside runs.

"Hitting the perimeter is probably a good play against us," Ferentz said. "We've given up more rushing yards than we care to, certainly ... that's what we're going to have to shore because I imagine we're going to see more of it."

Iowa's offense is another major reason why the Hawkeyes have been so up and down.

The Hawkeyes opened with a 12-play, 76-yard touchdown drive against the Gophers that included a number of third-down conversions. But Minnesota completely shut down the Hawkeyes until a meaningless touchdown pass from backup C.J. Beathard late in the fourth quarter.

Iowa also opened with a flourish at Maryland by jumping ahead 14-0 in the first quarter, before a 38-7 run by the Terrapins put the game out of reach.

Iowa has shown the ability to score points in bunches and play strong defense. But unless the Hawkeyes start doing more of both — and in the same game — they could be facing a tough stretch to end the season.

"There's no magic answers here," Ferentz said. "You've got to play well."

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Follow Luke Meredith on Twitter: www.twitter.com/LukeMeredithAP