Purdue hit the reset button on its defense during the offseason.

Jeff Brohm fired coordinator Bob Diaco after only one season — a 6-game season at that — then had to replace the rest of the defensive staff. He brought in Brad Lambert, formerly of Marshall, to be a co-defensive coordinator and play-caller, as well as linebackers coach; former Purdue assistant Mark Hagen to coach the D-line; James Adams to lead the cornerbacks; and veteran Ron English to coach the secondary, particularly the safeties. Three of the group — Lambert, Hagen and English — were given co-coordinator titles.

It wasn’t the end of the overhaul.

Purdue scoured the transfer portal as well, hoping to turn over its personnel in a way that could reshape the defense. And it scored big, drawing in 8 transfers, including 4 along the defensive line, a linebacker and 3 in the secondary.

Diaco’s defense, which was heavy on coverages and light on pressure, gave up 29.8 points per game last season, 8th in the Big Ten. It was the same ranking in yardage, allowing 399 per outing, with the pass defense sinking down to 12th in the Big Ten. But more than the numbers, Purdue’s defensive problems were more oriented toward scheme and personality. The Boilermakers’ chemistry, on its coaching staff and roster, suffered greatly. And it did show up on the field, with the defense getting progressively worse as the season wore on, giving up 20 points in its opener, but then 24, 27, 34, 37 and 37.

Lambert’s defense, a more traditional 4-man front, looks to be a better fit for the Boilermakers, taking advantage of their personnel — George Karlaftis needs to be featured, not played out of position — and playing with a more aggressive style that fits what Brohm wants to be.

Let’s play better or worse.

Pressuring the QB: Better

The pass rush was pathetic last season.

Harsh, but true. The Boilermakers had only 5 sacks, led by Karlaftis, who had 2 despite being healthy for less than 3 games. Diaco’s lie-in-wait style was unproductive and frustrating to watch.

Brohm, who is taking a more hands-on approach to managing Purdue’s defense this year, vows that the Boilermakers will be more aggressive, perhaps bordering on a go-for-broke approach.

It seems Purdue has the personnel to attack. Karlaftis, now a junior, is poised for a breakout season, assuming the 6-foot-4, 275-pounder can stay healthy. Last season, the second-team All-Big Ten member was plagued first by a leg injury, then by COVID. He can be a menace, but he’ll need help, and maybe it’s a slew of newcomers that provide the best chance.

One will not be Alabama A&M transfer Marcus Cushnie, a pass-rush specialist who committed to Purdue out of the transfer portal, only to head to Florida State instead.

Maybe Joe Anderson, a transfer from South Carolina who was on campus in the spring, can help. Purdue added veteran interior help as well, in the form of tackles Prince Boyd, a Last Chance U transfer (Independence CC), and Damarjhe Lewis, from rival Indiana.

But it might be a holdover who could take another step forward. Former transfer DeMarcus Mitchell had a solid debut as a Boilermaker in ’20, with 34 tackles, 6 for loss, and a sack. If he plays more end in Lambert’s system — rather than a hybrid in Diaco’s mixed front — then maybe he’ll be more active in the backfield.

Run defense: Even

It’s still somewhat shocking to hear, but Purdue’s run defense actually wasn’t all that bad last season.

It held opponents to 3.2 yards per attempt or less in 3 of its last 4 games. Not bad. The Boilermakers allowed 144.8 rushing yards per game, 6th-best in the Big Ten.

Purdue is hoping it can be better. Maybe all the veteran help the Boilermakers brought in can help, especially when considering they will be replacing two of their better run-stopping players. Although inconsistent, defensive tackle Lorenzo Neal could occupy blockers in the front. And linebacker Derrick Barnes had developed into one of the Big Ten’s best inside-the-tackles defenders. But both are graduated.

Veteran tackle Anthony Watts decided to return for a super season and is slated to start at one interior position. But the other one is up for grabs. The No. 1 option might be Lawrence Johnson, a reserve the last couple of seasons who has the size, at 300 pounds, to eat up space. Or maybe Branson Deen, who can play end or tackle, could win the spot.

Purdue is thin on experience at linebacker, with only Jaylen Alexander and Semisi Fakasiieiki having had experience. But transfer OC Brothers, from Auburn, could be an every-down player and Yanni Karlaftis, the jewel of the 2020 recruiting class, might be a starter from Day 1.

Pass defense: Better

The Boilermakers’ secondary has been a work-in-progress for about a half dozen years, maybe longer.

It was the same this offseason, when Purdue tried to retool the group by bringing in several veteran newcomers. And it continued to search the portal until the final day.

It added safety Christopher Jefferson from DII Findlay University, plus cornerbacks Jabari Brown (Kentucky) and C.J. McWilliams (Florida). Brown might get a shot to start — only veteran Cory Trice is inked in as one starting corner — but McWilliams’ career might be in jeopardy after an off-season accident, per a report from GoldandBlack.com.

With Trice and Brown, Purdue also has Dedrick Mackey, a solid coverage corner who has struggled in the running game. And there are a couple other promising underclassmen, although ones who don’t have any experience.

The same can be said at safety, where junior Cam Allen and sophomore Marvin Grant appear to have a ton of upside, but they’ve not put in a ton of snaps either. Jefferson might be able to push for more opportunity.

But whatever the combo, Purdue needs productivity. The Boilermakers gave up a ton of passing yards last season — 254.2 per game — while allowing QBs to hit better than 65 percent of their attempts. And Purdue had only 3 turnovers, which was somehow actually better than two other teams (Michigan and Maryland) in the Big Ten.

Special teams: Better

It’s shocking that punting didn’t cost Purdue 1 of its 2 wins last season.

The Boilermakers nearly gave it away vs. Illinois, saved only by the heroics of wide receiver David Bell. Inconsistent punting, to say the least, was a big-time issue, probably masked only by the fact that Purdue struggled in more high-profile spots.

But in his first season as the coordinator, Marty Biagi was forced to use 3 punters, all of that rotation due to production issues, not injury. Holding punting tryouts in the middle of the season is never a great sign.

Purdue recruited an outsider to try to fix the woes, signing 23-year-old rookie Jack Ansell out of Australia to compete for — and hopefully win — the starting job. Ansell trained at ProKick Australia, the same center that helped produce former IU punter Hayden Whitehead.

Last season, Purdue’s only scholarship punter, Brooks Cormier, punted 14 times, while walk-on Zac Collins, a rugby punter, had 10 and freshman Brendan Cropsey, who won the week-long punting competition, had his only attempt blocked. Even quarterback Jack Plummer punted twice.

Overall: Better

Purdue is certainly trying to fix its defense, replacing the entire coaching staff — only Diaco was fired — and recruiting 8 transfers.

It’s likely to help, particularly if Lambert finds a good mesh between his own approach and the Boilermakers’ existing personnel.