Purdue is not only an unranked team, it isn't even on the bubble of the AP poll.
In that sense, it would be easy for Denard Robinson and Michigan to take the Boilermakers lightly, especially since the Wolverines rolled over them last season, 36-14.
But Purdue's defense this season is different, and it matches up well against Robinson and Co. On top of that, the Boilermakers are playing at home, where they've blasted opponents by a combined score of 153-63. Purdue went 6-2 at home last season, including a 37-32 victory over Western Michigan in the Little Caesars Bowl.
Purdue possesses the same kind of Kryptonite against Robinson as Notre Dame did in Week 4. That is, the Boilermakers possess a good run defense.
As I've mentioned before, if you take away Robinson's running game and force him to air it out, good things will generally happen for you. Robinson rushed 26 times for 90 yards against the Fighting Irish in Week 4 (3.5 yards per carry) and responded by tossing four interceptions and averaging 5.8 yards per pass attempt.
Purdue is allowing just 3.3 yards per carry this season. The good news for Michigan is the Boilermakers haven't faced an explosive running game yet, so that number may be skewed. But there's no question a Purdue run defense that allowed 4.4 yards per carry last season has looked much better overall.
There's also Purdue's pass defense that could give Robinson troubles. The Boilermakers have allowed just 6.3 yards per attempt to opposing quarterbacks this season. And while they've allowed a middle-of-the-pack six passing touchdowns, they've also racked up eight interceptions.
For example, Marshall quarterback Rakeem Cato passed for 439 yards and five touchdowns against Purdue last week—at first glance, it may seem like he destroyed the Boilermakers pass defense.
But Cato also threw the ball 68 times—averaging 6.5 yards per attempt—and was intercepted three times. When you look at his overall numbers, his performance isn't as eye-catching.
Robinson threw 20 touchdowns last season, but he also tossed 15 interceptions in 13 games. He had thrown four interceptions in three games this season, even before the debacle against Notre Dame.
Purdue's defense may have faced lesser quarterbacks so far, but that doesn't change the fact that its capitalized on opportunities to pick off balls in the air.
I'm not saying that Purdue is Notre Dame, but there are plenty of reasons for Robinson and Co. to be well-prepared heading into West Lafayette.