Purdue’s defense exceeded all expectations last season.

And arguably, it was the biggest reason the Boilermakers ended consecutive seasons below .500 by winning 9 games, including the Music City Bowl over Tennessee. The defense kept Purdue in games in the first half of the season, until Aidan O’Connell took over as quarterback and the offense boomed, giving Jeff Brohm his most complete team in 5 seasons in West Lafayette.

But the offseason brought changes, both in the coaching staff — defensive coordinator and play-caller Brad Lambert moved on to Wake Forest after only a season — and in personnel, most notably the departure of NFL first-round draftee George Karlaftis.

Purdue, though, still thinks it has enough to put a good product on the field. Let’s make 7 way-too-early predictions about the defense:

Replacement issues

This isn’t a scalding-hot take: Purdue will struggle to replace Karlaftis’ production and overall impact.

Karlaftis’ statistics in 2021 — 5 sacks and 11.5 tackles for loss — belie his true value. He was a menace to most offenses, creating chaos in the backfield and allowing his teammates to thrive. Like a point guard in basketball who creates for others, Karlaftis was able to raise the level of play of his teammates.

Now, Purdue won’t have that A1 star defender who can take pressure off others. And where does the steady pass rush — Karlaftis, who was drafted No. 30 overall by Kansas City, was one of the nation’s leaders in quarterback hurries — come from? Veteran Jack Sullivan, who started the bowl game after Karlaftis had opted to prep for the draft, is likely to get a chance. He’s a solid, workman-like player. But maybe a true freshman, like Joe Sullivan or Nic Caraway, gets a crack at playing time.

By the middle of the season, if not earlier, look for Caraway to have gained an important role.

No change

Lambert spent only 1 season at Purdue, helping mold the Boilermakers into an aggressive unit.

Now, he’s gone.

But it’s unlikely Purdue will see a huge difference in approach, now that veteran coach Ron English, a D-coordinator, has been elevated to game-day play-caller. Last season, Brohm wanted a more collaborative effort on the defensive side, and he got that with a complete overhaul of the staff, which included Lambert, English and defensive line coach Mark Hagen.

English and Hagen are still around, joined by David Elson, who coaches the linebackers, and Ashton Youboty, who is in charge of the cornerbacks. It’ll again be a group effort, with Brohm taking a more hands-on approach, as he did a year ago.

The result will be that Purdue stays aggressive on defense, taking calculated chances that might result in a big play, but might also result in allowing one, as well.

Graham’s day

While a couple of the defense’s big-time play-makers are departed – namely Karlaftis and fellow end DeMarcus Mitchell — it gives another a chance to rise.

And the likely “Next Man Up” is hybrid linebacker/safety Jalen Graham, who has shown signs during his first 3 seasons in West Lafayette of being a big-time play-maker. The former 4-star recruit came to Purdue as a safety, transitioned to linebacker, and now will play a mixture of both, as English is likely to move the Boilermakers into more of a 4-2-5 formation.

It probably is the best for Graham, a 6-3, 220-pounder who has the agility to play in space but the physicality to play in the box. Against more physical opponents in the Big Ten West, like an Iowa or Wisconsin, look for Graham to be closer to the line of scrimmage. He could be more of a nickel back against teams like Nebraska or Northwestern.

And he’ll blossom. Last season, Graham had 64 tackles, 4 for loss, a sack and 2 interceptions, along with a team-high-tying 7 pass breakups and a forced fumble. He can do a little of everything.

Losing Grant hurts

Purdue got a surprise in early May, when starting safety Marvin Grant’s name appeared in the transfer portal.

It was unexpected, to say the least.

And now, the Boilermakers will have to deal with the loss — assuming Grant is departed and won’t return to West Lafayette — of one of their best and most experienced players. Grant was Purdue’s leading returning tackler, at 74, and showed at times that he could be a punishing hitter.

Now what?

Purdue likely will turn to Christopher Jefferson as an every-down safety, after the former transfer played mainly as the nickel back last season. And he played well, with 47 tackles, 4 breakups and a pick.

Better vs. the run

Purdue finished last season 12th in the B1G vs. the run.

It’ll be better this year.

That’s hard to imagine, considering Purdue lost 2 of its best defensive linemen, but Brohm loves Purdue’s depth up front, particularly on the interior of the d-line. There, the Boilermakers have veteran starters Branson Deen and Lawrence Johnson, but also quality backups like PrinceJames Boyd, Jr. and Damarjhe Lewis. The linebackers, mainly Kieren Douglas and Semisi Fakasiieiki are solid between-the-tackles ball-hawks (although they might struggle somewhat in space). It adds up to a Purdue team that, as a whole, will be better defending the run.

More interceptions

Purdue’s pass defense was greatly improved last season, ranking 5th in the Big Ten in allowing only 208 yards per game.

It’ll be hard to improve there.

But the Boilermakers could be even more opportunistic after generating 13 interceptions last season, which ranked as the 4th-best in the league. But with cornerback Cory Trice expected to return — he missed most of 2021 with ankle and knee injuries — Purdue potentially has one of the better cornerback tandems in the Big Ten. Former Kentucky transfer Jamari Brown proved to be a valued asset last season when he was forced into a bigger-than-expected role following Trice’s injuries. And he thrived. They are big, physical corners — both stand 6-3 — who can hawk the football.

And safety Cam Allen returns after having a team-high 4 picks last season. If Purdue can generate pressure up front, and that might be the big question, then it has athletes who can create turnovers in the back half of the defense.

Scoring … up?

Purdue very likely will give up more points per game next season than last, but that doesn’t necessarily mean it’s worse.

Why?

The offense is likely to be more consistent, and be able to score more quickly, than it did especially in the first half of last season. And if Purdue is scoring more behind the quarterback play of Aidan O’Connell, then each team is likely to get more possessions.

The Boilermakers ranked 7th in defensive scoring in ’21, allowing 22.4 points per game. It’ll be in the mid-20s this season, yet Purdue will still be competitive in the Big Ten West.