Spring practice is a time for optimism. Young players seize opportunities. Coaching tweaks fix last season’s flaws. And 15 practices — not to mention a slew of incoming freshman ready for action — have your favorite team poised for greatness.

Of course, that’s not always how it works out. But even the most even-keeled fans can’t help get caught up in spring fever.

As the Irish begin their preparations for 2014, changes made to the coaching staff, offensive and defensive scheme tweaks and roster additions have many fans feeling like 2014 is the year. But that’s hardly unique. You could basically write a column like this every year.

But with new defensive coordinator Brian VanGorder making significant changes to the Irish’s defensive scheme after four seasons under Bob Diaco’s watch, optimism is brewing. Perhaps it’s VanGorder’s SEC built and NFL tested scheme. It will have the young Irish unit playing an aggressive brand that hasn’t been seen in South Bend since the Holtz era.

But as Irish fans start their deep dig into next season, it’s worth setting some expectations for VanGorder’s defense. After following up Diaco’s four year run, what can we expect from VanGorder and his rebuilt unit?

Let’s dig in.

RESPECTING DIACO’S ELITE RUN AT NOTRE DAME

First things first. Bob Diaco’s four seasons in South Bend were more than impressive. They were elite.

Sure, there are detractors who grew tired of Diaco’s point prevention schemes and vanilla packages. Diaco operated conservatively, willing to give up a little to make sure he wasn’t beaten for a lot. The Irish defense gave up plenty of underneath opportunities to prevent the home run.

While 2013’s performance certain was a regression after 2012’s historic defense (loose underneath coverage doesn’t look so attractive when you’re also giving up the occasional long ball), it’s worth looking at this four-year breakdown of the best scoring defenses in the country to put into context the work Diaco did for Notre Dame:

Top Scoring Defenses, 2010-13*

1. Alabama, 11.0

2. Florida State, 15.1

3. Michigan State, 17.2

4. LSU, 17.4

5. Boise State, 17.8

6. Wisconsin, 18.3

7. Stanford, 18.9

8. Louisville, 19.0

9. Notre Dame, 19.1

10. Florida, 19.3

A top ten defense over the past four seasons is the definition of elite. Even if scoring defense isn’t your preferred measurement, advanced statistics are even more favorable for Diaco’s defense.

Take into consideration the slate the Irish play compared to the cupcakes Boise State, Wisconsin and Louisville routinely schedule, and it’s astounding to think that Diaco took Jon Tenuta’s damaged personnel and turned it into one of the most stingy groups in the country.

VANGORDER’S SCHEME

Entering his fifth season at Notre Dame, Brian Kelly’s defense is at a very different place than it was when he first came to South Bend. Because of that, VanGorder’s mission is different than the one Diaco was given.

Kelly gave us some insight into this before kicking off spring practice:

“When I hired Bob to come here, we needed to build consistency and stability with our defense, and he’s certainly answered the charge that I had given him,” Kelly said. “We needed fundamentally sound defense and we got that from Coach. “We have a great base, and we have now developed what we consider a demeanor on our defense and on expectation, and now we’re going to take it to the next level defensively and Brian is going to be able to take our defense to that next level, and I think that that’s what you’ll see in what Coach VanGorder will bring to our defense.”

Where we’ll see that from the start is scheme. Already, the Irish have basically turned into a 4-3 defense, likely looking more like Michigan State as it morphs into a 4-2-5 man coverage and pressure heavy scheme on passing downs than Diaco’s traditional two deep zone defense.

Diaco kept his base defense on the field quite a bit, at most swapping in an additional defensive back or downsizing the dog linebacker against option teams. That’s likely changing with VanGorder from the opening snap if we are to believe what we’ve seen in the Irish’s first practices.

Speedy linebackers Jaylon Smith and Joe Schmidt will likely improving the Irish’s underneath coverage while skill players like John Turner and converted receiver James Onwualu infuse athleticism that Carlo Calabrese and Prince Shembo didn’t have in space.

While Kelly has held true to the line that the defense will still base out of a 3-4 set, the secret that the Irish will be playing a 4-3 primarily is largely out. And if our early viewing windows into the Irish defensive strategy have been any indication, sub-packages will be the new norm, likely with hopes of improving the Irish’s performance on third down and creating sacks and turnovers while defending the pass.

Again, Kelly’s remarks from his spring practice presser give you an idea that while the objectives are still the same, how they achieve those goals will change.

“Third down packages, we’ll be able to use personnel uniquely different in certain areas,” Kelly said. “But at the end of the day, this is still about keeping the points down and taking the football away and eliminating the big plays.”

PERSONNEL QUESTIONS

Of course, one reason the Irish might have a heavier reliance on scheme is because they have to rebuild their defense. Gone are Louis Nix and Stephon Tuitt, two defensive linemen that Stanford’s David Shaw considered among the top five in the country.

Fellow building blocks Prince Shembo, Bennett Jackson, Dan Fox and Carlo Calabrese have also departed, as well as key sub Kona Schwenke. How much will that effect the Irish’s play? It’s still tough to tell.

Spring certainly will mask any deficiencies. Yet trying to figure out how good VanGorder is for this defense will depend an awful lot on how good the players taking snaps end up being.

Notre Dame already saw what a scheme heavy coordinator hire will do when there are deficiencies at the core. Jon Tenuta only returned to the coordinator ranks last season at Virginia after three seasons coaching linebackers at NC State after his flame out with the Irish. Utilizing a pressure and scheme heavy formula (sound familiar?), the Irish defense became one of the ultimate boom or bust units in the country, with bust happening far more often than boom.

It’s hard to look at the inexperience on the roster and think it’s as raw and underwhelming as the units that Tenuta put on the field. But the peanut butter and mayo pairing that Brown and Tenuta created in 2008 is worth remembering. After all, it was the transition from Brown’s 3-4 base system to Tenuta’s attacking 4-3 that imploded the Irish, producing a defense befitting a roller derby team.

Credit Kelly for understanding that any change needed to be done whole sale. That’s why Kerry Cooks title demotion from co-defensive coordinator to secondary coach made sense. There can only be one leadership voice, and this unit is most certainly VanGorder’s.

(Have a look at Eric Hansen’s most recent work in the South Bend Tribune, and it’s clear that one voice stands alone at the top.)

But Kelly also understands clearly that any amount of scheme and strategy only works if you can implement it. So while a faction clings to success in the SEC or being one of the NFL’s better coordinators with the Falcons, Kelly put an emphasis on the ABCs of coaching when he introduced VanGorder.

This is as close to a manifesto on coach hiring as Kelly’s ever delivered.

“The first thing I wanted in this position is a great teacher,” Kelly said. “I think first and foremost when you’re talking about the ability to bring together our defensive players, you need the ability to communicate and to teach, and Brian is one of the very best teachers, if not the best teacher, that I’ve ever been around, and I go way back with Brian. So first and foremost he’s a great teacher.

“I think the second thing that stands out is he understands player development, and so anyone that I want to be around on a day‑to‑day basis has to understand the important principles of player development in bringing them along and really understanding how important it is to get those traits out of our players. They’re not ready made. The players that we bring here to Notre Dame, we have develop them, and not just on the football field, but off the field as well. Brian understands that. His background coming with me, starting at Grand Valley State, but before that, being a high school coach makes him uniquely qualified to understand player development, being at the high school ranks, being in division II at Georgia Southern as a head football coach, being in the SEC, obviously being in the NFL, understanding player development was huge in the selection of the defensive coordinator here.

“His experience, let’s understand that. We’re at the University of Notre Dame. We’re playing for championships, and so the defensive coordinator needed to have that experience. Brian has that national experience. He’s a two‑time Broyles Award winner for the finest assistant coach in the country. So he has that resume, has that experience as a defensive coordinator in the SEC. And he’s also sharpened the iron in the NFL as well in building that experience.”

Teach. Develop. Experience. That’s a hire that makes sense.

CONCLUSIONS COME IN AUTUMN

For as good as the hire of VanGorder looks on paper, ultimately the results on the field will tell the story. While we can dissect any Xs and Os or philosophical tweaks, the defense doesn’t exist in a vacuum, and VanGorder will be taking cues from Kelly on how the defense fits into the Irish’s overall game plan.

But the challenges are steep. Rice and Michigan provide immediate challenges. Stanford, North Carolina and Florida State could be a meat grinder three weeks. A November filled with Navy, Arizona State, Northwestern, Louisville and USC sounds no easier. So even if VanGorder’s defense statistically takes a step backwards, it could be miracle work with this unproven group.

There’s a lot to decipher between now and Rice’s journey to South Bend on Labor Day weekend. But one thing is clear:

There’s work to be done and VanGorder has already gotten started.

*Stats provided by the website formerly known as BlueGraySky.