It's hard to know exactly what to expect from North Carolina heading into Wednesday's game at No. 1 Michigan State.

The Tar Heels are out of the national rankings after losses to two unranked teams. Yet they've also beaten reigning national champion Louisville. And it has all come as the team plays without leading scorer P.J. Hairston and senior Leslie McDonald due to unresolved NCAA eligibility concerns.

Coach Roy Williams said Tuesday the wild swings are a sign of how his current bunch has a small margin for error as they face the Spartans in the ACC/Big Ten Challenge.

"We have to play really well," Williams said. "And that being the case, it's like golf. You can't go out and think you can shoot 75 and nobody's going to pass you."

The Tar Heels (4-2) lost at home to Belmont on Nov. 17, giving up the go-ahead 3-pointer in the final seconds in a game where they missed 26 free throws. It was North Carolina's first nonconference home loss in eight years.

A week later, they followed a win against Richmond in the Hall of Fame Tipoff semifinals by upending then-No. 3 Louisville for the title.

They followed that with Sunday's 63-59 loss at UAB, coached by longtime Williams assistant Jerod Haase. The Tar Heels trailed by 15, took a beating on the boards and shot 1-for-12 from 3-point range.

Now the Tar Heels, ranked No. 12 in the preseason, are unranked.

Ask Williams if there is any explanation for the roller-coaster ride, and he'll jokingly respond that he'd have already fixed the problem if he knew what it was.

"We love what we did against Louisville," sophomore forward Brice Johnson said. "We're disappointed about Belmont and UAB. But you just have to keep going. You just have to forget about what happened. You can't really forget about it, but get over it and keep playing because at the end of the day you have another game coming up."

Michigan State (7-0) hasn't faced those kinds of struggles. The Spartans beat Kentucky last month, their only game decided by fewer than nine points.

And coach Tom Izzo isn't spending a lot of time trying to figure out the cause of UNC's struggles in a rematch of the 2009 NCAA final won by the Tar Heels. Rather, he said he's focused on his improving his own his team, which has been "fairly consistently consistent" compared to most of college basketball.

"We're finding ways to win games and move on," Izzo said. "You've got to be getting better and I think we're at least addressing those things. And so we're in a decent spot right now, not a great spot."

As for UNC's Hairston and McDonald, Williams said there has been no change in their status. The two haven't played at all this season and haven't traveled for road games while the school works with the NCAA to resolve their status amid questions of possible improper benefits violations.

Until then, the Tar Heels have to solve their problems without them.

"In '09, we could play really poorly and still win a lot of games," Williams said. "We don't have that margin."


Follow Aaron Beard on Twitter at http://www.twitter.com/aaronbeardap