Posted by ESPN.com's Adam Rittenberg
Five lessons from the week that was in Big Ten football.
1. Iowa is for real -- Some Hawkeyes fans might have misinterpreted my postgame commentary. True, Penn State made mistakes Saturday night, but Iowa forced them with terrific defense and special teams. The Hawkeyes put themselves squarely in the Big Ten title mix with Ohio State by stunning the Nittany Lions for the seventh time in eight tries. Defense and special teams are the formula for success on the road, and Iowa executed both areas to perfection in the first of four challenging Big Ten away games. It's hard to imagine a defensive line in the country playing better than Iowa's.
2. Scott Tolzien is also for real -- The quarterback position must improve in the Big Ten this year, and Tolzien has done his part for the 4-0 Badgers. He has validated the coaches' decision to start him, throwing for 221 yards per game with eight touchdowns and two interceptions. Tolzien picked apart a vastly overrated Michigan State secondary in Saturday's victory, passing for four touchdowns, three to tight end Garrett Graham.
3. Tressel ball still works -- Much like Iowa, Ohio State has gotten better every week of the season despite some lingering issues on offense. Credit quarterback Terrelle Pryor and running backs Brandon Saine and Dan Herron for making key plays against Illinois, but Ohio State won with defense yet again. The Buckeyes haven't allowed a touchdown since Stafon Johnson's run at the end of the USC loss, shutting out consecutive opponents for the first time since 1996. Head coach Jim Tressel's formula continues to click in Big Ten play.
4. Press the panic button for several teams -- Illinois and Michigan State both should be in panic mode after getting dominated -- the Illini more than the Spartans -- in critical road tests on Saturday. Both teams were projected to be in the Big Ten's upper half, and now both could be fighting for their postseason lives when they meet Oct. 10 at Memorial Stadium. Northwestern also should be extremely worried because of a defense that has regressed fundamentally and that shocked head coach Pat Fitzgerald with its poor tackling. Purdue can't seem to get over the hump in close games, and Danny Hope could have a long first season in West Lafayette.
5. Michigan's defense has major issues -- Tate The Great showed up again in the fourth quarter Saturday to secure a 4-0 start for Michigan, which continues to pile up points. But if the Wolverines continue to play defense like they did against Indiana and for most of the game against Notre Dame, they won't be undefeated for long. Youth, size and depth are hurting Greg Robinson's defense right now, and things need to get fixed as Michigan hits the road for the first time and faces better competition in October.