Updated

The turnover problem that plagued Nebraska a year ago has returned with a vengeance.

The Cornhuskers head into this week's trip to Penn State with 10 turnovers in the last 10 quarters. In the last five games, they've had 16 turnovers and only three takeaways.

They had five turnovers in Saturday's 41-28 loss to Michigan State — the most since they lost the ball eight times in a loss to Iowa State in 2009. Michigan State converted the turnovers into 24 points.

"Dumbfounded. Just dumbfounded," offensive coordinator Tim Beck said. "We put a lot of emphasis on it, and for the most part this year we've been a lot better. Those mistakes today were ... ugh, I can't put a finger on it."

During the spring and in preseason practice, coaches had put the offense through special drills focusing on ball protection. They've seen no improvement. In fact, the Huskers have gone from being 108th nationally in turnover margin to 110th.

Nebraska (7-3, 4-2 Big Ten) won the turnover battle in three of its first five games and was even in the other two.

The recent problems have coincided with the change at quarterback, from the injured Taylor Martinez to Tommy Armstrong Jr.

Armstrong has thrown seven interceptions and fumbled twice in his last four games. Against Michigan State he threw an interception in the first quarter, fumbled in the second and again in the third on a play from his 1-yard line.

That last fumble, on the exchange from center, set up a Michigan State touchdown that made it a 13-point game late in the third quarter.

All five of Nebraska's turnovers against the Spartans occurred on its side of the field, with three inside the 25. The Spartans had touchdown drives of 8, 22 and 3 yards.

"It's frustrating," linebacker David Santos said, "but we play defense with the mindset that we're going to get the stop every time."

Compounding the Huskers' problems Saturday was their defense's inability to get off the field. Michigan State converted 11 of 21 third downs against a defense that had ranked third in the country in third-down defense at 27 percent.

"That could be one of the biggest stats of the game," linebacker Michael Rose said.

Beck and the offensive players probably would disagree. Since 2010 the Huskers are 21-1 in games in which they are plus-turnovers and 15-14 when they are even or minus-turnovers.

Five turnovers were simply way too many.

"You can't beat a bad team with five turnovers," Beck said, "let alone a team like Michigan State. You can't give them opportunity after opportunity after opportunity. They're going to win."