“Watch out.”

That’s what Godwin Igwebuike had to say about Northwestern’s defense back in April. As the defensive back enters his senior year, he knows that, because of the success the Wildcats have enjoyed over the past two seasons, there’s a higher level of expectation.

Igwebuike was specifically talking about Northwestern’s secondary when he said those two words. And it’s probably the best phrase to summarize a unit that returns three of its four starters from a year ago. But it won’t be just the secondary that should be on the radar screen. As a whole, the defense has an opportunity to build on its reputation as one of the best in the nation.

Northwestern isn’t often associated with “nation’s best” in anything related to college football, so that statement may come as a bit of a surprise. That’s been the case since 2015, though.

It’s easy to make that claim by going through the game logs from the past two years and glancing at the final scores. The Wildcats have ranked in top 25 nationally in scoring defense each of the past two seasons, allowing 18.6 points per game in 2015 and 22.2 last year. Games are a lot easier to win – especially in the B1G – when your defense is that stingy.

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The Wildcats have found success at keeping teams out of the end zone by winning the important battles. They’ve gotten off the field on third down and tightened up in the red zone. Northwestern has ranked in college football’s top one-third in several critical defensive categories.

While most of the numbers from last year aren’t quite as good as in 2015, there wasn’t a huge decline.

Northwestern Scoring defense Total defense Opp. red zone TD % Opp. 3rd down conv. %
2016 22.2 (T-23rd) 404.4 (60th) 48.2% (13th) 36.6% (33rd)
2015 18.6 (12th) 318.9 (13th) 56.8% (49th) 32.6% (15th)

Despite that slight drop off, there’s reason to believe Northwestern will rebound this fall. The defense could be as effective as it was in 2015. Hence the “watch out” comment.

Igwebuike is coming off a year in which he posted a team-best 108 tackles, recorded two interceptions and broke up seven passes. But he’s just the starting point for the secondary. Montra Hartage intercepted five passes last season, which was the second-best tally in the B1G. Kyle Queiro and Jared McGee were also significant contributors a year ago.

Losing Trae Williams to a leg injury in the spring is a setback and limits the secondary’s depth, but the nucleus should still be pretty effective.

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That group did have its struggles in 2016, ranking last in the B1G in pass defense, but it was also one of the most opportunistic. Those four accounted for 12 of the Wildcats’ 16 interceptions. Don’t be shocked if the “no fly zone” moniker travels from East Lansing to Evanston.

And even with the loss of Anthony Walker, Jr., Northwestern isn’t exactly desperate at linebacker. Nate Hall and Brett Walsh will hammer down two of the spots, leaving just one open for competition. While nobody is going to replicate Walker’s presence in the MIKE role, returning two with starting experience is an asset.

Northwestern’s attempt to continue its string of efficient defensive seasons doesn’t come without challenges, though. The biggest obstacle comes on the defensive line. Though Walker was the Wildcats’ best defender the last two years, losing top pass-rusher Ifaedi Odenigbo is probably the most difficult to replace, especially with Xavier Washington’s indefinite suspension and uncertain future.

The line struggled to get pressure on the quarterback last year and had issues disrupting the backfield. If Washington can’t play, The Wildcats have just one lineman – Joe Gaziano – that recorded a sack in 2016. It puts more pressure on veterans like Tyler Lancaster and Jordan Thompson to have a bigger impact. Regardless of who it is, Northwestern desperately needs someone capable of chasing down the quarterback to maintain its defensive prominence.

But the Wildcats have a lot to work with. If the defense can find that pass-rusher, it’s hard to imagine Northwestern doesn’t have a season similar to 2015. And if that’s the case, they’ll be a serious contender to Wisconsin in the West.

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Northwestern has won 17 games over the last two years. It’s been dominant on third down and has been tough inside the red zone. In those critical areas, the Wildcats have been exceptional. Most of those 17 wins can be attributed to that mentality.

Heading into 2017, Igwebuike and the secondary appear to have the right mentality and are ready for big things this fall.

If the rest of the defense follows suit, watch out.