It was such a given that Iowa's defense would be stout that it has almost been overlooked this season, especially after the team lost at Arizona.

It's doubtful the rest of the Big Ten feels that way.

The defense for No. 17 Iowa is coming off yet another dominant performance and appears to be peaking heading into league play. The Hawkeyes (3-1) held Ball State to just 112 yards of offense — 56 on the ground, 56 in the air — in thumping the overmatched Cardinals 45-0 last week.

Iowa ranks first in the nation with 227.5 yards allowed per game. The Hawkeyes have also allowed just 14 points in three games at home headed into Saturday night's Big Ten opener against No. 22 Penn State (3-1).

"Everyone is working together, growing up and maturing and doing their job," Iowa cornerback Shaun Prater said Tuesday.

And doing it without defensive coordinator Norm Parker the past few weeks.

Parker, considered one of the top defensive coaches in the country, has been hospitalized because of complication with diabetes. Parker won't coach against Penn State, but coach Kirk Ferentz has indicated that Parker could make the Oct. 16 trip to No. 19 Michigan.

"Getting his strength back is paramount. It's not going to be this week. We'll take it a week at a time, see where we're at," Ferentz said. "They're just trying to map out the next move. But I think we're getting close to making a move."

Iowa's defensive staff has shared duties in Parker's absence, an arrangement that's proven successful.

"We're better with Norm. There's no question about it. But if he's not here — and it's just kind of like if I get hit by a bus this afternoon, somebody's going to have to jump in there and take my role for a little while," Ferentz said. "Everybody just rallies together, does what they have to do."

Iowa's defense did have one misstep this season, but it was a big one.

On Sept. 18, Iowa rallied to tie Arizona at 27-27 in the fourth quarter on an interception return by Broderick Binns. The Hawkeyes then let the Wildcats go on a long touchdown drive late in the fourth quarter, which wound up costing them the game.

"We're not perfect. Going back to the Arizona game, there's plays there that got us beat," safety Tyler Sash said. "Stats really don't mean anything if you don't get the win."

Arizona's game-winning TD came on arguably the only meaningful scoring drive Iowa's allowed all year.

The Wildcats also scored on an interception return and a kickoff return and racked up another TD after blocking a punt inside Iowa's 10-yard line. Iowa State scored its only points in garbage time of a 35-7 loss by using its starters against Iowa's reserves, and FCS school Eastern Illinois used a perfectly executed fake punt at its own 20 to set up its lone touchdown.

More often, opponents have found themselves either turning the ball over or sending in the punt team against Iowa; 40 percent of drives against the Hawkeyes this season have ended in three-and-outs.

"I think the defensive guys have done a great job, players and coaches. That's kind of what you'd expect. I think we've good people here that pull together when things happen," Ferentz said.