I'd go with Malik Hooker. Penn State games over the years have often turned on a big special teams or defensive play and I could see that happening again Saturday. Hooker's the best Buckeye defensive playmaker I can think of dating back to the mid 90s.
Close second for me would be Billy Price. MJ's performed admirably so far but lots of low snaps against TCU and I can see that being an issue Saturday in that crazy environment.