Two things stand out in this comparison of Ohio State's and Tennessee's NEM season trand (these are 5-game running averages):
Net Efficiency Margin offense (blue)/defense (red) splits (all charts here are 5-game running average NEM)
First, Tennesee's spike around game 15, which corresponds to their win over Kansas. Over a six-game stretch (December 31 at Memphis to January 19 at Alabama), the Vols averaged a 30.8 NEM. After that spike, they began a slow upward climb that approached but never quite reached the 30 NEM level. As the offense/defense split chart shows, this improvement has been driven by defense. Their offense has been fairly pedestrian for most of the season.
Net Efficiency Margin offense (blue)/defense (red) splits (5-game running average)
The other obvious feature is that Ohio State with Evan Turner has been a very consistent team. I've already covered this, but it's even more obvious in this chart. After Turner's return (game 19 is the first where the 5-game running average fully includes Turner), the Buckeyes have essentially hung out at the 30 NEM level. For the full season, that would be better than any other team in the Sweet 16 except Duke.
Each team's respective strengths - Ohio State's offense or Tennessee's defense - should roughly cancel out, so it could come down to which of the weaker units comes through. Ohio State's weakness - their defense - is still ranked in the top 25 nationally, so I'll go with the Buckeye's here.