If you had to use one word to describe No. 8 Notre Dame’s defense coming into this year, it had to be “experienced,” right?

When the Irish walked off the team bus in Culver, Indiana, for training camp in August, they returned 10 starters from last year’s team. Only senior cornerback KeiVarae Russell, who was a two-year starter before missing last season due to suspension, hadn’t started for Notre Dame in 2014.

And with an inexperienced quarterback, who was supposed to be junior Malik Zaire, the defense should have been an area of strength for Notre Dame this season, a pillar to lean on with one of the most talented groups in the country.

But that never panned out.

When former defensive coordinator Bob Diaco left to take the head coaching job at Connecticut two years ago, Irish head coach Brian Kelly tagged Brian VanGorder to be his replacement. Unlike Diaco’s “bend, don’t break” system that worked so well in 2012, and earned him the UConn job, VanGorder came in with a different attitude: Be aggressive.

And at the start of his tenure, it seemed like VanGorder had things figured out. In the first five games of 2014, his defense gave up just 12 points per game and routinely pressured opposing quarterbacks, including the four sacks racked up by the Irish against Stanford in a key 17-14 win.

Then everything changed.

North Carolina threw 43 points onto the Notre Dame Stadium scoreboard the next week, everyone got hurt, and suddenly the Irish defense that looked so good in September looked so bad in November.

But this year, there was hope. Everyone but cornerback Cody Riggs was back — and even after senior defensive lineman Jarron Jones went down, VanGorder had everything he could have asked for in a defense: a potential top-10 pick in Jaylon Smith, surrounded by a wealth of experienced talent. The idea was simple: Led by Smith and senior defensive lineman Sheldon Day, we would finally see Notre Dame run VanGorder’s defense to perfection.

On opening night at Notre Dame Stadium, it looked like it could be the case, when the Irish trounced Texas 38-3, racking up four sacks en route to a dominant performance.

But just like the previous year, it was a false dawn for VanGorder’s defense.

A week later, a Virginia team — one that got its head coach fired after a 4-8 finish — moved the ball all over the Notre Dame defense in a game that the Irish probably should have lost.

And in Notre Dame’s two losses this year, the defense consistently put the offense in tough situations. Within the blink of an eye at Clemson, the Irish were down 14-0, and Saturday, we saw what may have been the worst performance of the year from VanGorder’s unit in the biggest game of the season.

Despite containing Stanford’s Heisman Trophy candidate, sophomore running back Christian McCaffrey, the Irish defense still struggled massively on the West Coast. The defense got out of the gates slowly and couldn’t get off the field Saturday, as Stanford went 8-for-12 on third downs, including a perfect 5-for-5 performance to start the game.

While McCaffrey didn’t do too much to hurt Notre Dame, it was Devon Cajuste who proved to be the problem. The Irish secondary routinely lost the senior receiver, including on the defining moment of its season, a 27-yard completion between Stanford senior quarterback Kevin Hogan and Cajuste on the final drive, when the Cardinal picked up the chunk of yards required to set up the game-winning field goal.

It was a perfect microcosm of Notre Dame’s season on defense, one filled with so much potential and occasional execution but never finding that four quarters of consistency Irish head coach Brian Kelly so often spoke of wanting from the defense.

After Texas, we never really saw VanGorder’s defense play his scheme well — the Irish finished outside the top 70 nationally in sacks, with just 23 on the season — and never saw it play any scheme particularly well.

And if VanGorder couldn’t get it to work with this unit, what are we supposed to expect out of it next year?

Graduate student linebacker Joe Schmidt, senior safety Elijah Shumate, senior defensive lineman Romeo Okwara and Day are all out of eligibility. If Smith and Russell declare for April’s NFL Draft, like most of us think they will, Notre Dame’s defense will return just five starters from this year’s team when it opens its season in Austin, Texas, in September.

That doesn’t even count graduate student cornerback Matthias Farley, whose loss will also likely be felt in a big way.

VanGorder couldn’t get his scheme to work particularly well with an incredibly experienced crew this year — to expect anything different next year would be irresponsible.

I don’t want to explicitly call for VanGorder’s head. After all, watching him on the sidelines is a particularly enjoyable part of watching Irish football.

But Notre Dame came up short of fulfilling its goal this year — and Kelly would be wise to at least evaluate VanGorder’s merits prior to 2016.

The views expressed in this column are those of the author and not necessarily those of The Observer.