How can Ohio State’s vaunted defense get even better?

He wants a top five defense this fall.

Not top five overall — which he had statistically last season — but rather top five in everything.

Is that ambitious?

Absolutely.

Is it realistic? Maybe not.

But this is preseason, a time for both hope and hyperbole so Ohio State fans should probably be happy to hear such high talk from the leader of a once-proud defense that has shown progress the last two seasons under Knowles but still has areas to improve.

“Always learning,” Knowles said. “Always studying because Year 1 (we were) aggressive, gave up some big plays. Year 2, we were top five in (preventing) explosive plays but not as good in sacks and lost yardage plays, so it’s a constant balance — tinkering with it.”

For context, let’s look back at where Ohio State was a top five defense last season, the areas that were close and the ones that need the most improvement to achieve Knowles’ expectations, including traditional stats and advanced stats.

Already top five (rank):

Pass defense (1), yards per pass (1), total defense (3), pass efficiency defense (2), scoring defense (2), third down defense (5), yards per play (3)

Odds are good the Buckeyes will be good against the pass again. They return their top four cornerbacks, safety Lathan Ransom is back from a season-ending foot injury, and they added Caleb Downs, who was a Freshman All-American safety at Alabama last season.

That also comes in handy on third downs and helps keep down yards per play since many more explosive plays are going to come through the air.

Almost top five:

Power/short yardage run defense (6), red zone (12), first downs allowed (8), rushing defense (27), yards per carry (22), rushing yards (27), success rate (12), explosiveness rate (11)

Being good at stopping the pass and short-yardage runs seems like a good formula for success, but Knowles seems to want more than “good.”

Then again, living with a few rushing yards during the course of a game if it helps avoid explosive plays is an emerging strategy in today’s college football, so that is also a tradeoff Knowles is likely comfortable with.

That is especially true if a defense can do it while maintaining a high success rate, which measures how often the offense gains five yards on first down, half the yards to gain on second down and all the yards to gain on third and fourth down.

Areas for major improvement:

Defensive line yards (53), stuff rate (87), havoc rate* (68), front seven havoc rate (79), defensive back havoc rate (53), sacks (64), tackles for loss (71), turnovers gained (121), interceptions (109)

Overall, the Buckeyes were good at avoiding explosive plays, but they did not make a lot of big plays themselves, either.

Those things likely went hand in hand.

Ranking sixth in power conversion rate, which measures success against the run on third- and fourth-and-short, indicates the Buckeyes could stop the run when they were geared up to do it.

The other numbers show teams could find some running room the rest of the time.

Defensive line yards are an advanced stat that attempts to credit (or discredit) the front seven for run defense by filtering out runs of more than four yards that can skew the data, so teams were able to make successful short runs with some consistency even if they rarely hit home runs on the ground.

That can be remedied in multiple ways, including the defensive linemen and linebackers simply making more tackles or by adding another player to the box such as a safety (which could in turn lead to more big plays allowed).

Lack of tackles for loss would hurt that average and indicate the Buckeyes were not as active attacking the line of scrimmage, as does a poor stuff rate, which measures how often an opponent’s runs went for no gain or a loss.

Knowles suggested he could blitz more but also do a better job at preventing the offense from having an idea when a blitz might be coming.

“We want to emphasize those things that we can get better at. Being a Silver Bullet defense means being a top five defense,” Knowles said. “So we had some significant top fives, but not all of them. So then we look at those things that can make a difference, like the presentation of our defense. That’s a big deal.

“Are we showing what we’re playing? Now you can get into the details. Are we showing what we’re playing or are we disguising? And then, blitzing. We need to be more aggressive in terms of the calls, getting more blitzes run, more pressures run, getting our D-line into one-on-one matchups.”

*Havoc combines rate of plays that involved a tackle for loss, forced fumble, interception or pass break-up.