ANN ARBOR, Mich. – When the Michigan and Michigan State football teams meet in Ann Arbor this weekend, the focus will be on each team's defense.
The Wolverines own the No. 1 defense in the country, allowing 203.3 yards per game, while the Spartans are fifth, allowing 248.3 yards per game. Saturday's rivalry game should be a low-scoring battle, which is nothing new for either team.
Even though defense will dominate on the field, the most intriguing offensive storyline has to be the comparison between starting quarterbacks John O'Korn and Brian Lewerke.
For the Spartans, Lewerke has been the man for the job all along. He was the best option in 2016 before breaking his leg against Michigan, and he's shown improvement this season.
Michigan is in a completely different situation. Starter Wilton Speight was knocked out of the game against Purdue, and O'Korn took over for his first meaningful snaps since the opener against Florida.
But there wasn't a dropoff when O'Korn entered the game. In fact, it was the best Michigan's offense has looked all season, with O'Korn leading four touchdown drives and finishing perfect in the red zone.
Lewerke and O'Korn both add the extra dimension of a running quarterback to the offense, though Lewerke seems much more eager to run the football.
Lewerke is Michigan State's leading rusher this season, turning 38 carries into 248 yards and two touchdowns. He's difficult to sack because of his mobility in the pocket, and his legs can turn a broken play into a big gain.
O'Korn showed an ability to scramble for a first down when he started for Speight against Indiana last season, but at Purdue, he wasn't looking to advance the ball on the ground.
O'Korn had one very good run for 12 yards, when he stiff-armed a defender and plowed through another for a first down. But when he moved around in the backfield, he was doing so to extend plays and look downfield.
The most memorable example came when Michigan was backed up deep in its own end. A Purdue defender broke into the backfield untouched, and O'Korn ducked under him, spun out of a tackle and ran to the right of the pocket. Instead of trying to turn the corner, O'Korn planted and threw a strike to Grant Perry, who was running over the middle.
It turned into a much bigger gain, and O'Korn didn't have to take a hit.
Lewerke's greatest improvement so far this season has been his accuracy, completing nearly 9 percent more of his passing attempts than a year ago.
His 63.2 percent completion rate hasn't come at the expense of throwing the ball downfield. He's actually averaging more yards per catch this season than in his first taste as a starter.
O'Korn has never been a quarterback who completes 60 percent of his passes, even at his best. During his excellent freshman year at Houston, when O'Korn threw for 3,117 yards and 28 touchdowns, he completed 58.1 percent of his passes.
Last year as a backup, O'Korn completed 58.8 percent of his passes.
When he took over against Purdue, O'Korn showed improved accuracy, completing 18 of 26 passes (69.2 percent) for 270 yards. It's hard to believe O'Korn has simply become a more accurate passer after four years in college, but working with Harbaugh can only help.
Lewerke did some of his best work against the Notre Dame defense, when he completed 31 of 51 passes for 340 yards and two touchdowns. The stage won't be too big for him, but Michigan will field the best defense he's seen in his career.
Harbaugh doesn't ask much from his quarterbacks -- they have to run the offense and make the short, easy throws to move the chains. Even when Speight was struggling in the passing game, Michigan was winning games easily because of its defense and special teams.
O'Korn didn't play like a game manager at Purdue. He made all the easy throws and even connected on a few passes downfield. His mobility, especially in escaping pressure, is an added bonus.
Lewerke, on the other hand, has been all of Michigan State's offense. The Spartans' running backs are averaging fewer than 4 yards per carry, so he's doing most of his damage without a rushing game.
As the runaway leading passer and rusher on the roster, Lewerke shoulders much more of the burden than Michigan's quarterbacks.
Who has the QB advantage?
If John O'Korn is really the quarterback we saw against Purdue, then Michigan might have a player better than Lewerke, but at this point, that's too much of an assumption.
Lewerke has been steady for Michigan State, even though Western Michigan's 41st-ranked defense is the best he's seen this season. He's more dangerous running the football, and he's had more time to prove himself as a passer than O'Korn.
Even though O'Korn's ceiling, which he demonstrated his freshman year at Houston, is more or less the same as Lewerke's, it's the unknown that holds him back. He hasn't started a game this season, and it's difficult to pass judgement until he does.
Michigan State goes into the rivalry game with a slight advantage at the quarterback position, but a major advantage in terms of stability at the position. The Wolverines have had questions surrounding their quarterbacks all season, but for the Spartans, Lewerke is clearly the leader.