Ohio was more than a little bit lucky. They benefited most in those aspects of the game that are least predictive. By predictive I mean that some that some stats are very good at predicting future performance, like yards per carry. Other stats are less predictive, e.g., opponent field goal percentage (see Penn State v. Virginia). Ohio lost only five fumbles (but dropped the ball 13 times) and threw only five picks all season. They turned the ball over on 6.7% of possessions, third best in the country. Turnovers cost them less than 3 points per game. Holding on to the ball is a skill, but turnovers are as much or more about luck as skill, and Ohio had a lot of it.
Besides avoiding turnovers, Ohio benefited from good average starting field position (own 32) and good play on 3rd down, which led to longer drives (5.7 plays per possession). That's not luck. That's good football. They attempted a field goal on 17.5% of possessions and converted on 13.3%, 8th most nationally. In other words, the offense did a good job of squeezing points out of possessions, despite averaging only 3.7 points in the red zone, and of not putting the defense in bad situations.
On defense, aspirations for mediocrity were undermined by poor performance in the red zone (5 points per trip) and on 3rd downs (44% conversions allowed on 3rd and 4th downs, 25th worst nationally).