Big Ten power rankings: Week 2

One week of Big Ten action is in the books, and we finally have some on-field evidence to judge these teams.

Michigan State remains the class of the league after a hard-fought win against Boise State that shouldn't have been as close as the final score (17-13). The Spartans boast an elite defense and an elite running back (Le'Veon Bell), but they have work to do if they want to remain No. 1. Michigan only moves down a spot despite its blowout loss, in large part because Wisconsin let off the gas against FCS Northern Iowa. There's very little separating the teams 2-5 , and we'll get a better read on Ohio State when the competition improves.

Purdue and Illinois look like the best of the next tier, and Penn State moves down a few notches after its season-opening loss to Ohio. But again, teams 6-10 are very, very close.

Here we go ...

1. Michigan State (1-0): The defense can take the Spartans a long way, and so can Bell, although it's unrealistic to expect him to have 44 carries and 50 touches each game. Quarterback Andrew Maxwell must make strides this week against Central Michigan before another home showdown against Notre Dame on Sept. 15. Maxwell needs to better handle the pass rush and show more touch on his passes. If he can do so, Michigan State's ceiling is very high.

2. Nebraska (1-0): All eyes were on Taylor Martinez after all the offseason talk of improved mechanics and football, and the Huskers' junior quarterback delivered. Martinez looked much more comfortable throwing the ball en route to a career-high 354 pass yards in an easy win against Southern Miss. His progress offset the loss of top running back Rex Burkhead. We'll learn more about Nebraska after it hits the road this week to visit UCLA, but so far, so good.

3. Michigan (0-1): Alabama makes a lot of teams look bad, and most of Michigan's Big Ten brethren would have difficulties hanging with the Tide. But Saturday's 41-14 loss exposed Michigan's weaknesses, particularly at the line of scrimmage, as well as a lack of depth at key positions. The injury fallout doesn't help the Wolverines, who lost starting cornerback Blake Countess to a season-ending ACL tear. They'll need young and unproven players to step up during a tortuous schedule.

4. Wisconsin (1-0): Rather than the typical September laugher at Camp Randall Stadium, Wisconsin found itself in a major scrap Saturday against Northern Iowa. The Badgers nearly squandered a 19-point lead in the fourth quarter and looked shaky at times in defending the pass. The good news: new quarterback Danny O'Brien played an efficient game (19-for-23 passing, 219 yards, 2 TDs, 0 INTs). But this was far too close for comfort against an FCS foe, especially at a place where Wisconsin has been so dominant.

5. Ohio State (1-0): To repeat: there's very little separating Ohio State from Wisconsin and the other top Big Ten squads. We were very impressed with Braxton Miller and the debut of the new Buckeyes offense in Columbus. But Miami (Ohio) didn't provide much of a test for Urban Meyer's crew, which might not get one until Week 5 at Michigan State (although this week's opponent, Central Florida, could be tricky).

6. Purdue (1-0): Despite the suspension of top quarterback Caleb TerBush, Purdue made quick work of Eastern Kentucky and looked like a team that could take the next step this season. Robert Marve is capable of leading the offense and should push TerBush this week in practice, and Purdue did what it had to do against inferior competition, piling up 547 yards of offense and converting 12 of 15 third-down chances. But the Boilers move up several classes this week against Notre Dame, and we'll know much more about Danny Hope's squad in four days.

7. Illinois (1-0): The combination of a banged-up Illini secondary and a prolific opposing quarterback (Alex Carder) suggested a potentially rough debut for coach Tim Beckman. But Illinois took control of the game and never really let Western Michigan in it. The Illini defensive line still looks very strong despite losing first-round draft pick Whitney Mercilus, and it held WMU to minus-6 rush yards. Illinois' main concern is the health of quarterback Nathan Scheelhaase and an offense that didn't produce much and will need a stronger effort Saturday night at Arizona State.

8. Iowa (1-0): Although many folks expected Iowa's opener to be close, few saw things going the way they did Saturday afternoon at Soldier Field. Iowa's two shakiest positions, defensive line and running back, both delivered with nice performances, as Joe Gaglione (3 tackles for loss, 1 forced fumble) and Dom Alvis (2 tackles for loss, 1 sack) sparked the line and Damon Bullock piled up 150 rush yards. Senior quarterback James Vandenberg struggled and Iowa trailed most of the way, but it's a win and an opportunity to build.

9. Northwestern (1-0): Credit the Wildcats for another season-opening road win against a major-conference opponent, but their blown lead and defensive breakdowns create unease going forward. Northwestern never looks comfortable playing with a lead, although it never gives up, either, and received a big boost down the stretch from backup quarterback Trevor Siemian. Still, the defense showed major weaknesses that future opponents will expose, beginning this week with Vanderbilt.

10. Penn State (0-1): After a strong start to the Bill O'Brien era, Penn State faded on both sides of the ball in the second half Saturday. The offense needs to finish drives and create a better run-pass balance, which could be tough if Bill Belton is sidelined for an extended period. A big concern is a Lions defense that surrendered 499 yards to Ohio and struggled to get off of the field, allowing 13 of 21 third-down conversions. The defense must respond in a hurry as the nonconference schedule has no sure-fire wins.

11. Minnesota (1-0): The Gophers found a way to leave Las Vegas with a victory, as they received a strong effort from the defense and the running backs. MarQueis Gray came alive in the overtime sessions, but the senior quarterback will have to be much more polished for Minnesota to beat better competition. The Gophers also must play more disciplined after being flagged 11 times in the opener. New Hampshire is a solid FCS program, and Minnesota can't take anyone lightly after falling to FCS North Dakota State by 13 points last season.

12. Indiana (1-0): Any win is valuable for the Hoosiers, who matched their victories total from 2011 on Saturday night, but they'll need to make significant strides going forward. IU has to shore up its rush defense after allowing Indiana State's Shakir Bell to rack up 192 yards Saturday night. The pass rush looked improved, though, as Indiana racked up five sacks. That's a nice building block, as is quarterback Tre Roberson's strong performance. Indiana aims for its first FBS win under Kevin Wilson this week against new FBS member Massachusetts.