Notre Dame legend Manti Teo knows true talent. He knows explosiveness.

The NFL player also has insight as to the level of play expected this year from his former teams defense-as a former defensive star himself.

From SI.SanDiego, Teo commented:

"Young,explosive.." 

Simple logic says replacing NFL talents like Stephon Tuitt and Louis Nix would be difficult at best.

While at Notre Dame, the two became instant fan favorites, morphed into top college talents and provided Notre Dame with one of the nations best overall defensive units during their National Championship run in 2012.

Last year, the defense as a whole took a step back, Nix and Tuitt never fully recovered from injuries and the Irish defense from a year prior became an afterthought.

For the Irish in 2014, replacing any player is all but a distant memory and no longer an option.

Not because the talent isn't around.

It is there.

But along with several changes from uniforms to field surfaces- the Irish defense will morph into a 3-4 defense this season under new defensive coordinator Brian VanGorder.

Notre Dame will have to utilize the entirety of the roster to the best of their abilities and do it fast.

Players like Nix and Tuitt aren't walking into the GUG anytime soon.

And that presents oppurtunities for several players,freshman included- to see action this year, and it will also involve seasoned veterans in a new role.

In 2012, the defense drove the bus to the BCS Championship game for Notre Dame.

As players board the bus this season, it's clear that the offense could dictate the overall success for the Irish.

But a closer look into what Brian Kelly has with his defense this year shows a roster capable of providing another spark to elevate the team back to the BCS spotlight.

Defensive Line

The phrase "it all starts up front" will be the underlying statement attached to the Irish this season.

Expectations are being levied on the shoiulder pads of more than just 2 players heading into the opener in late August.

Injured players like Tony Springman and Chase Hounshell must return to provide needed depth.

As a group, no greater focus will be placed on one sole unit as there will be on the defensive line.

Sheldon Day will take on the role of Nix and Teo in the eyes of the coaches. He will need to be disruptive and command leadership from the entire team.

On the field, the 6'2" 290 pound Day is very nimbel and explosive for a player his size. Perhaps more agile and quick then Nix.

Although his 33 tackles last season pale to modest standards, his ability to breakthrough the line of scrimmage will be his calling.

Brian Kelly about Day's first-step quickness and intensity:

"He has incredible ability to rush the passer for an interior defensive lineman," Kelly said. "He's very unique in that sense. Most of those guys are two-down players, where you get 'em off the field on third downs. He could arguably be our best pass rusher as an inside guy. We may have to move him outside on third down. He has a unique skill set. He can be great against the run on first and second downs, and then on third downs can offer the ability to rush the passer. He's got a very good work volume for us. I think he's gonna be a terrific defensive lineman for us."

For Jarron Jones, it's all about snaps.

Jones will add size to the line with his 6'5" 300 pound plus frame.

And his limited role last year simply was a case of whom he played behind, and progression from time spent on the practice squad.

 Kelly admires the talent inside the player, regardless of the path to getting on the field:

“You know, when they go down on scout team, I get eyes on them because I’m over with the offense.  So I was able to evaluate his demeanor, the way he came and worked every day.  We were looking for consistency, a consistent effort.  We think he’s got a lot of skill, great size.  We wanted to see that fire every single play, and I liked what he did in the couple of weeks that he was down with us, and that’s why we elevated him back up with our varsity group,” Kelly said.

The two most intriguing players of the group remain to be Ishaq Williams and Romeo Okwara- the starting ends this season.

Talent accompany both.

Williams carries a 4/5 star rating when he entered Notre Dame-something he's yet to live up to.

Okwara provides quickness off the edge with a 6'4" 260 pound body. He will fill the gap left by Prince Shembo.

This is the area that is most crucial heading into 2014- the edge rush.

Williams and Okwara and their backups must play to their projected stars and abilities for more than just one game to breed success overall for the Irish defense this season.

Linebackers

While replacing Nix and Tuitt will be a task, replacing Manti Teo was almost an overnight transition.

Jaylon Smith is the next great linebacker in college football.

Actually, he's already that and more.

The Butkus watch list player will be the biggest role player for VanGorder's 3-4.

With 67 tackles as a true freshman, the heralded recruit not only delivered by filling Teo's shoes in a short window, but he provided the team with a much needed pass coverage from the outside spot.

Smith took over for Danny Spond after head injuries cut his playing career short.

From there, Smith played like a veteran. He recorded his first career interception in the USC game and nobody can forget his star power on football's grandest stage.

During the Arizona State Shamrock Series game in Dallas at Jerry's World, Smith moved all over the field and played one of the most fascinating games any freshman Irish player ever has.

And he did it against an offense known to present difficulties to defenses with one of the nations top mobile quarterbacks-Taylor Kelly.

The career upcoming for Jaylon is limitless as to what he will accomplish and provide Notre Dame.

He will command play on the field that will force offenses to rethink the direction of each play, and he almost assuredly will provide a much needed boost of leadership overall-hopefully accompanied alongside Jarrett Grace.                                                                                                                                         

The player most likely to move into the spotlight with Smith will be walk on Joe Schmidt. His knack of picking up the schemes of the defense has earned him playing time over scholarship players and a boost in coaches confidence-applying the tag of 'Next Man In' over coveted recruits.

Injuries plagued a couple of players in Doug Randolph and Ben Councell.

Randolph sat out last year with his injury, and projections of incoming freshman Nyles Morgan moving into the depth chart could push a player like Councell into an end role.

Jarrett Grace remains a bit of mystery at this point.

 

As Smith was playing the role of superstar in the Arizona State game, it took the sting off of Grace's injury received on the same night.

The original heir apparent to Teo, Grace has endured surgeries to not only mend the original injury to his leg, but to thwart complications during the healing process.

Earlier in June, Coach Kelly updated his progress:

 "We’re going full-go for him to be ready for Rice.He wants to do it that way. He’s very encouraged. I think it’s the best I’ve seen him mentally. He was in a tough spot there for a little bit before the surgery. It was good to see him in very good spirits today. We’re going to be very aggressive with him, let him go and I think if we really went slow with him, it would probably put him in jeopardy for being ready for the first three, four weeks. That’s not what he wants. We’re going to go at it and go for the best."

Overall defensively, this unit remains the biggest question mark for Notre Dame this season.

Last year during the OU game, 1 play exemplified the problem concerning not only depth-but players understanding their role based on their talents. And coaches not fortified with the right talent to offset certain parts of the game led to issues all season long.

The play involved a subpar receiver getting underneath the defense in Sterling Shephard. With around twelve minutes left in a 1 score ball game, Blake Bell hit Shephard underneath for a modest play that turned into a 54 yard game clinching touchdown.

Poor attempts at tackling became the norm, and not just in this game.

On this day, the roles of only a year removed were reversed.

All day the Sooners ran outside on the Irish, and underneath passes plagued them as well.

Stoops had a simple plan: attack the weakness of the linebackers.

It was something plaguing the Irish defense all year long in 2013.

2014 will remain a work in progress for the unit, but success based on projected depth and incoming players from recruits to rehabed veterans should provide enough ability to offset last year's troubles.

Secondary

If there is one area that will flat out be fun to watch, it's this unit.

And the player that will anchor this unit is KeiVarae Russell.

Russell has played as many games then the remainder of the unit individually, and brings into this season a load of confidence to go along with his heralded recruiting status and potential to not only be one of the nation's best "shut down corners"- but to be the best:

“My goal is to win the Thorpe this year,I don't want to win it next year. I want to win it next year, but I'm not trying to say I'm going to wait until my senior year. I want to win it this year. That's a big goal for me, to win the Thorpe this year. I think I really I can. The biggest thing for me is perfecting my craft and becoming a true lockdown corner. I know I can.”

Where Russell, Mathias Farley and Austin Collinsworth bring a leadership aspect, the talent's of elite safety Max Redfield and corner Cole Luke will be called upon this season to provide depth by moving into cemented starting roles.

Luke projects out as the other corner opposite Russell, and Redfield will move into a starting role at safety.

This is where it gets interesting for the unit.

Incoming transfer Cody Riggs from Florida.

Riggs, a one time Notre Dame recruit, is a player that is going to play right away and add more depth and proven time on the field after playing within the SEC:

"He will help us immediately but, more importantly, Cody is a great kid with a tremendous focus on both football and academics. His decision to complete his collegiate playing career and pursue a graduate degree at the University of Notre Dame speaks volumes about both our program and University.”(Brian Kelly)

The question will remain who pushes who aside this season. Luke has all but secured his role, but having the luxury of a speedy shut down player like Riggs will be intriguing to watch as the summer progresses and the season plays out.

And there's Max Redfield.

Under Armour selection.

Elite 5 Star recruit.

The "Project X" of players.

Freak athlete.

In the words of Coach Kelly:

"Crazy, crazy, crazy ability.He can make a mistake and get himself out of it. ... We’re still in the learning curve with Max, but he’s so gifted. You’ve gotta get Max Redfield ready. We’re going to get him ready.”

Coach Kerry Cooks:

"He's going to be a heckuva player.He's just got a lot to learn. Very talented kid."

Put on ice and eventually released to the viewing public late in 2013 in the Pinstripe Bowl-Redfield looked the part. Redfield started the game at safety and appears in line to move forward.

'Youth' is an appropriate word when describing the secondary for the Irish in 2014.

But there may not be a more talented core of players overall in college football.

Incoming Recruits

Jay Hayes and Nyles Morgan will not only play in 2014 as freshman, but both could very well see a major role and perhaps rotate from game to game.

At 6'4" 275, Hayes will quickly remind Irish faithful of Nix.

Recruited by the likes of Alabama, Georgia, Florida and Florida State,Hayes will be called on early given the depth issue on the defensive front behind Day and Jones.

Tony Springman and Chase Hounshell will fill the depth chart, providing their health doesn't limit production, but Hayes will push for playing time..

And should Hayes step onto campus above his 275 weight or near, he will be pushed into the defensive tackle role as opposed to the end position.

Morgan will play in 2014,no matter how unsettled the linebacker position appears today for Notre Dame.

Another elite talent recruited in the mold of Teo and Jaylon Smith, Morgan will provide quickness and recognition ablities to a much needed area.

Drue Tranquill could provide even more depth to the questionable linebacking core for the Irish- and he could also fill in on special teams.

While being recruited, the Irish coaching staff reminded Tranquill of his need and oppurtunity to step in soon in 2014:

“They were talking about my spot and the needs they have. It’s not that deep at linebacker. They were telling me, ‘Hey, we don’t have a third-down linebacker, we need you to learn the defense as fast as you can so you can come in and potentially help us at that Sam position.’”

Talented like Morgan, and a hitter- best describes what Tranquill will bring to South Bend.

There are some very talented defensive players coming in this year's freshman class. And there is a huge window for any of these recruits to play.

Overall Outlook

In 2013, the Irish gave up an average of 22 points per game.

In 2014, a tougher schedule gets even tougher allowing that potential of scoring.

Arizona State,USC,Florida State,Louisville and even Michigan will bring enough offense for any defense to have trouble defending.

And especially a defense not exactly aware of how good it can be or will be.

The opposite side of the ball could provide the Irish defense some relief now that the quarterback spot is a little more settled as opposed to last year, along with a stronger running game.

The problem in the OU game again can't be said enough that after the Shephard score, the Irish offense couldn't return the favor.

That shouldn't be the case this season.

The work to bring a return game up to a respectable level continues as well, and it will need to keep the offense in comfortable situations to provide the defense as much cushion as possible early in the season until they gel and enter into the heart of the season and a grueling stretch of games.

Rice, Michigan, Purdue and Syracuse will be a basic window to tweek, mold and glue together what ever plan Brian VanGorder has pieced together for the 2014 Irish defense.

Leadership roles will need to be established in summer practices heading into the season.

This unit has it's work cut out for them.

There's no time to look through doors for legends to walk through and shore up the line of scrimmage.

The time is now for players like Ishaq Williams to bring to the team the projected talents they were recruited for.

An Elijah Shumate must elevate his game as well to compliment the talented group of secondary players that will be the heart of this year's defense.

Projecting a run stopping elite unit that was the 2012 team is something many shouldn't attempt to do as it is but a pipedream of sorts.

Ideally, keeping teams from exploiting the underneath area of the field will be the primary focus.

If the defense can sustain and prevent the Sterling Shephards of the world from converting 10 yard receptions into game killing touchdowns, good things are going to happen.

A long season awaits this team if modest plays aren't kept at bay.