MORE: Five questions for Northwestern's offense

Northwestern's spring practices got started on Tuesday, and there are no shortage of questions facing the Cats coming off a 3-9 season.

Lots of them center around a defense that turned in a shockingly bad performance in 2021. Here are five questions that defensive coordinator Jim O'Neil and his unit will hope to answer, or at least begin to answer, this spring:

For the first five games of 2021, Northwestern's defense couldn't stop a chair. Michigan State, Duke and Nebraska did whatever they wanted; those three teams averaged 41.3 points per game against NU.

Thankfully, the bye week following the 56-7 disaster in Lincoln gave the coaching staff a chance to make some much needed changes to the defensive scheme. O'Neil had attempted to install his 4-2-5 "star" defense, but for one reason or another it did not work.

After the bye week, Northwestern came out against Rutgers in a base 4-3 defense and sat in cover-four most of the time, similar to what they did under previous DC Mike Hankwitz. Northwestern played much better on defense from that point forward (save for the Illinois game, which was more of an effort issue than a scheme issue), playing less 4-2-5 and more 4-3.

They turned in strong performances against Rutgers and Iowa, and did a good job of bending but not breaking against Michigan and Minnesota, despite being on the field for two-thirds of the game. Even against Wisconsin, four of the Badgers' five touchdown drives came with stating field position of midfield or better. The defense was constantly set up to fail by the offense in the second half of the season.

The post-bye NU defense showed enough promise to be hopeful that improvements from retuning players, along with new additions from the portal and through recruiting, could help boost a 4-3-based Cats' defense back to the level of play they demonstrated in the years before.

However, leaving the star defense in the past is no sure thing. With another year under their belts, the Wildcats' defenders should be more comfortable running it. Plus, you have to figure that coaches selected the incoming Wildcats to fit better into the scheme.

Northwestern still may not have a great option to play the titular star position. Rod Heard II was asked to play the role last year, and he was little undersized to play in the box as much as the star is asked to. Ideally, it would be a safety/linebacker hybrid playing there; someone like incoming freshmen Robert Fitzgerald or Devin Turner, if they are anywhere near ready. If NU wants Heard II to reprise his star role, he would have to have had put on weight this offseason.

O'Neil knows what defense he will run in 2022 -- whether it will be a star, a 4-3, or a littel bit of both. The spring is a chance to find the right players to fit in the chosen scheme and set the unit up to get back to playing at the level expected of a Northwestern defense.

One of Northwestern's first additions out of the transfer portal was UMass defensive tackle Taishan Holmes. Holmes is a mass of humanity, listed at 315 pounds on the Minutemen roster -- and that may be a kind number.

Holmes is a true nose tackle, something Northwestern never needed when they played a four-man front. The recruitment of Holmes, paired with NU coaches telling recruiting targets that the staff envisions them playing nose tackle, has made the switch to a 3-4, or even a 3-3-5, in Evanston seem imminent.

O'Neil comes from the Rex Ryan coaching tree, just like Wisconsin defensive coordinator Jim Leonhard. The Badgers have run a 3-3-5 with great success during Leonhard's tenure. Could Northwestern be making a switch to emulate their Big Ten west rival?

In addition to Holmes, the player on NU's roster best suited to play nose tackle is junior Jordan Butler. He didn't see much playing time last year, but listed at 316 pounds, he has the prerequisite size to play the nose.

It was strange to see a Pat-Fitzgerald-coached team struggle so much to find good linebacker play, but that was the case in 2021. With Chris Bergin and Peter McIntyre's careers coming to an end, only Bryce Gallagher returns with significant playing time in purple.

The first transfer to commit to Northwestern this offseason was linebacker Wendell Davis Jr. from Pittsburgh. Davis had 44 tackles, five for loss, and two sacks in his Panther career. He will join the Cats halfway through spring practice when the university's spring quarter gets started. The practices before Davis arrives will give some young players a chance to make some noise.

In terms of veterans, Khalid Jones is back as a middle linebacker. But he hasn't played much football for the Wildcats, just eight games in four seasons in Evanston.

Whispers out of the ever-secure Walter Athletics Center are that three young Chicagoland products have separated themselves from the pack in the linebacker room: redshirt sophomores Greyson Metz and Xander Mueller, and redshirt freshman Mac Uihlein.

Metz, a Glen Ellyn Glenbard West graduate, famously turned down a scholarship offer from Iowa to walk on at Northwestern. He appeared in eight games last season on special teams, making one tackle.

Mueller, a graduate of Wheaton North and the younger brother of former walkon linebacker Erik Mueller, got some run at the end of last season in place of McIntyre and showed a knack for making plays. Against Wisconsin, Mueller had eight tackles and forced a fumble. He also tallied a half-sack in Northwestern's blowout win over Ohio. His total 2021 season stats in eight games were 19 tackles, .5 sacks, one forced fumble and one fumble recovery.

Uihlein, from Lake Forest, came to NU with the most fanfare as the top-ranked recruit in the state of Illinois in the class of 2021. He didn't see the field at all in 2021 as he worked to get stronger and be able to handle the physicality of the Big Ten. Now, in year two, he seems poised to make the leap to a contributor.

Linebackers coach Tim McGarigle has no shortage of options to fill out the linebacking corps in 2022. Four of them are guys who didn't play much last season -- which, given NU's struggles against the run, might be a good thing.

His 4.5 sacks might not jump off the page, but Adetomiwa Adebawore was a force off the edge for the Cats in 2021. He wreaked havoc on opposing quarterbacks every week; he just didn't have any help. Even when Adebawore got after the quarterback, passers had plenty of escape room as no one besides Adebawore was able to generate any consistent pressure.

Samdup Miller and Jeffery Pooler Jr. both exhausted their eligibility in 2021, so Northwestern will be looking for some fresh faces to take a step forward. One of those will be redshirt sophomore Sean McLaughlin, who was the fourth defensive end in the rotation last season. McLaughlin made 12 tackles in 2021 and had 1.5 sacks. At six-foot-five and 265 pounds, McLaughlin is still skinny; that's something that the strength and conditioning staff has surely been working on with him this offseason. If McLaughlin can get some more meat on his bones, his length gives him potential to be a threat rushing the passer.

Redshirt senior Devin O'Rourke is a defensive end who came to Northwestern with a considerable amount of hoopla as the No. 3 prospect in Illinois and a four-star, Rivals250 prospect for the Class of 2018. Things haven't gone the way anyone hoped so far in O'Rourke's career. He has zero sacks or tackles for loss through four seasons and has only made seven total tackles. He has dealt with injuries that limited him to just five games over his first two seasons and stunted his development. If he can stay healthy, he has a chance to live up to the hype he came to Evanston with in what could be his final season.

Other DEs we haven't seen much of are Jaiden Cameron, Aidan Hubbard and Najee Story. If Northwestern is indeed going to a three-man front on defense, there are more avenues for the Cats to find Adebawore some help with an "edge" outside linebacker. Four-star freshman Anto Saka could be the type of talent who could push for playing time in his first year, but he did not enroll early so he would have to get caught up in a hurry during training camp. Additionally, linebacker Grayson Mann has filled in as a speed rusher in the past and could take on that role.

Safety Brandon Joseph sent shock waves through the Northwestern community by announcing his intention to transfer to Notre Dame earlier this offseason. There aren't many positive ways to look at someone with Joseph's history leaving the team, but if there is one hopeful spin it's that, while Joseph was an All-American in 2020, he was the Wildcats' second-best safety in 2021.

Coco Azema wasn't even a starter to open the season, but by the end he might've been the best player on NU's defense. Azema was fourth on the team with 72 tackles, despite missing a game. He made 3.5 tackles for loss, broke up four passes and forced two fumbles. He was also a hammer in the running game. Having Azema back is a huge boost for Northwestern. The Texas native played linebacker in high school, and said he still likes to channel his past self and come downhill and hit people.

That's what separated him from Joseph last season. While Joseph struggled with missed tackles, Azema was one of Northwestern's most reliable tacklers. Having a safety like Azema, whose strength is run support, will be a big part in improving NU's run defense in 2022.

Replacing Joseph next to Azema will, ironically, be another Joseph: Jaheem, in all likelihood. Jaheem has been praised as a very smart and instinctive player who is ready to take on a big role this season. He didn't see the field much last year as he was in the process of changing positions from cornerback. If the excitement around Joseph is to be believed, he and Azema could form a potent duo at the back end of the defense, and help Northwestern fans move on from BJo's departure.