But barring special teams scores and turnovers, each team is going to get the same, or very close to the same, number of offensive possessions. So, except situationally (e.g., trying to score with no time left for the opponent's offense at the end of the half or a game), I wouldn't think that tempo matters much. You're going to be on defense for roughly half of the possessions in most games no matter how fast or slow you play. Given that base level of equality, what a team should want to do is whatever maximizes the expected points per possession when on offense and minimizes the expected points per possession when on defense.
IMBSO, where Ohio State has often left meat on the bone in this regard is in poor starting offensive field possession resulting from lousy punt fielding/returning, poor defensive field position resulting from often mediocre punting, and, as great as the defense has been this year, in not forcing many turnovers or causing much "havoc" (e.g., in many circumstances, getting a sack on an opponent's 3d and 12 seems worth a fair amount more to me in terms of expected points on the next offensive possession than giving up 9 yards even if both results get the defense off the field). Of course, forcing "havoc" with blitzes creates risk, which is why being able to get great pressure on the opposing QB with a four man rush is, to me, a huge key to success. I'd also submit that trying harder to block punts might be something worth pursuing.