Clemson's defense heads into proving ground against Notre Dame

Two weeks ago, in the second half of Clemson's tightly contested matchup against Louisville, the Tigers' defense was presented with four opportunities to cling to a single-digit advantage against Bobby Petrino's offense. Sophomore quarterback Deshaun Watson & Co. had just broken a 10-10 tie with a 25-yard strike late in the third, but very little was going right for the typically high-powered attack. The Tigers needed stops.

Preseason odds frowned on Clemson winning such games in 2015.

The program's defense served as a primary pipeline to the 2015 NFL Draft, placing standouts like Vic Beasley, Grady Jarrett and Stephone Anthony on pro rosters, which left decorated defensive coordinator Brent Venables in need of seven new starters while trying to emulate one of the best units in program history. Set aside hot-shot play-caller Chad Morris and the well-oiled spread-option machine: Clemson was a defense-first program in 2014. Maintaining that level of excellence is difficult.

And despite the foreshadowing provided by head coach Dabo Swinney — saying there would not be much, if any, decline if the Tigers stayed healthy — there were justifiable doubts about whether they could come close to last season's No. 3 scoring defense nationally.

"I didn't think we'd have a big drop-off if we could stay healthy with our first group. That's kind of how it's played out," Swinney said earlier this week. "As you know, we're really young and inexperienced behind those guys. That's why getting guys playing time here and there is huge for us. Because somewhere along the line as we go through the course of the season, some of those guys right now that nobody's talking about, nobody's asked me about, nobody, some of those guys somewhere are going to have to step up for us by November."

Swinney's premonition held true against Louisville.

A healthy Tigers defense forced two interceptions, a turnover on downs and a missed field goal in the final 17-plus minutes to secure the 20-17 win over the disappointing Cardinals. 

It was another notch on the belt for a program that, perhaps quietly, continues to morph into a defensive stalwart under Venables. Clemson rarely finds itself in the back-and-forth shootouts that defined the early Swinney years. This season, defensive end Shaq Lawson is pulling off his best Beasley impression by living in opponents' backfields, top cornerback Mackensie Alexander anchors a disruptive secondary and the unit as a whole has forced five turnovers in the past two games.

Openers Wofford and Appalachian State certainly aided the transition process, but No. 12 Clemson still ranks sixth in opponent-adjusted efficiency (S&P+ rankings) this season.

"I just think they're extremely athletic. I know a lot of these guys are first time starters, but they've played a lot of football," Notre Dame coach Brian Kelly said. " ... From the defensive end position all the way back to the cornerback position, it will be the most talented and athletic defense that we've played this year."

That's a two-way street, though.

No. 6 Notre Dame's offense is, by far, the biggest challenge this Clemson defense has faced to date. In fact, of the five ACC teams ranked top-10 nationally in scoring defense, Clemson is the first to line up against a top-10 offense. Here's a look at the league's top four defenses and their respective schedules to date (opponent-adjusted offensive efficiency rankings in parentheses):

In other words, outside of Boston College hanging around with a new-look Florida State offense still trying to replace the No. 1 NFL Draft pick with a graduate transfer behind center, the highest-rated offense any top ACC defense has faced has been ... Texas State. (Of course, this early in the season the defensive efforts against those teams skewed the statistics, but it's safe to say, barring midseason turnarounds from Georgia Tech or Louisville, there's not a juggernaut on that non-conference slate.)

In a recent piece, SBNation's Bill Connelly, whose efficieny ratings are found above, tabbed the ACC as the best defensive conference to date according to his metrics. The numbers are the numbers, and there has certainly been surprising production from the likes of Duke and Boston College. Still, Saturday's high-profile matchup will provide a welcome on-field barometer on where this Tigers defense, carrying the mantle for the ACC's top units, stands on a national scale.

The Fighting Irish come in with their own question marks: Kelly's team has been ravaged by injuries, with the losses including its starting quarterback, running back, tight end, defensive tackle and nickelback. The backfield hasn't missed a beat with redshirt freshman quarterback DeShone Kizer and running back C.J. Prosise (fifth nationally in rushing), though, and Swinney said this Notre Dame team as a whole might just be better than the 2012 edition that scrapped its way to the BCS title game.

As for the challenges for the Tigers' defense, Notre Dame's varied schemes should keep Venables & Co. on their toes.

"They're going to pick their spots with their tempo," Swinney said. "They have a lot of speed sweeps, lot of stretch zone, lot of counters, lot of power, lot of quarterback run designed, quarterback run plays, lot of zone read, lot of boots, big on the screen game. Lot of max protection, one- and two-receiver routes. Take a ton of shots down the field whenever they get man-to-man coverage.

" ... They're by far the best team we've played. They're the best offense. They're the best defense."