Posted by ESPN.com's Adam Rittenberg

Five lessons from an utterly wacky Week 9 in the Big Ten (blame it on Halloween).

1. Iowa can be very explosive on offense: Rallies are nothing new for Iowa, but the Hawkeyes normally use defense and special teams to erase deficits. Many doubted whether the Hawkeyes had enough offensive firepower to bounce back after really struggling for the first three quarters against Indiana. But quarterback Ricky Stanzi and wide receivers Marvin McNutt and Derrell Johnson-Koulianos answered those questions with a huge fourth quarter against Indiana, which blew a 14-point lead. Iowa exploded for 28 points in the final 11:38 and finished with its highest scoring total (42) of the season despite committing six turnovers. The Hawkeyes simply own the fourth quarter this season, outscoring opponents 100-38.

2. Big Ten officials had a very rough Halloween: Unlike the SEC and the Pac-10, the Big Ten never comments on officiating, but the league can't be pleased with what took place Saturday. There were several questionable calls and a few total misses, and instant replay seemed to make the problems even worse in most cases. The league will remain tight-lipped on this subject, but you can bet there will be consequences. Michigan State head coach Mark Dantonio can't be pleased with the men in stripes right now.

3. Minnesota can score without Eric Decker: Sometimes it takes an unfortunate event for a team to reach its potential. Minnesota hadn't found any offensive consistency this season outside of Decker, who suffered a season-ending foot injury last week at Ohio State. Playing without the star wide receiver, the Gophers turned in their best offensive performance of the season against a very formidable Michigan State defense. Quarterback Adam Weber passed for 416 yards and five touchdowns, and offensive coordinator Jedd Fisch was extremely creative in his play-calling. Good to see from the Gophers.

4. Michigan is a mess: After a 4-0 start to Year 2 of the Rich Rodriguez regime, Michigan is falling apart at the seams. I'll admit I was wrong about these guys and particularly the defense, which seems to have regressed under first-year coordinator Greg Robinson. The Wolverines surrendered 500 total yards, 377 rush yards and 38 points to an Illinois team that hadn't scored more than 17 against an FBS team all season. If the defensive woes aren't bad enough, Rodriguez has a major problem at quarterback as freshman Tate Forcier struggled again. "We're not getting wins that we should, we're just playing for pride now," safety Troy Woolfolk said. Wow.

5. Wisconsin is making strides: The Badgers delivered the most complete performance of any Big Ten team in a conference game Saturday, totally dismantling Purdue at Camp Randall Stadium. Running back John Clay was dominant, and the defense shut out a league opponent for the first time since 1999. Losses to Ohio State and Iowa likely will keep the Badgers out of the Big Ten title race, but they are clearly the league's fourth-best team and could get into a Jan. 1 bowl. Head coach Bret Bielema and his assistants deserve credit for getting this program back on track after an extremely disappointing 2008 campaign.