Notre Dame will transition into next season with its defense in flux.
The Irish will enter 2014 without their top two defensive linemen, looking to replace five starters in their front seven and being guided by a new defensive coordinator.
Defensive end Stephon Tuitt became the latest defensive loss for Notre Dame on Sunday when he declared for the NFL draft.
The 6-foot-6, 312-pound senior posted on his Twitter account: "Thanks for a wonderful three years at the best University on earth. I will forever be IRISH." Sports Illustrated first reported Tuitt's decision not to return for his senior season.
Tuitt was slowed at the start of the season as he continued to recoup from surgery to repair a sports hernia. But after collecting four tackles in the first three games, he closed the season with 41 tackles, including 7 ½ for loss and six sacks.
Tuitt is the second defensive lineman to decide to leave Notre Dame with a year of eligibility remaining.
Nose guard Louis Nix III signed with an agent last month ending the chance for the senior, who didn't play as a freshman, to return for a fifth year. Nix, who was lost of the last two regular-season games with a knee injury and the Pinstripe Bowl, had 27 tackles with two for loss last season.
Notre Dame will return only defensive end Sheldon Day from its opening day starting line, and the Irish will also have to replace graduated linebackers Prince Shembo, Dan Fox and Carlo Calabrese in the front seven.
Day, a 6-2, 290-pounder, was slowed by an ankle injury during his sophomore season. He had 23 tackles with 3 ½ for loss and two sacks last season.
Linebacker and former Bishop Luers star Jaylon Smith is the only other player in the Irish's starting front seven from opening day who will return.
The 6-2, 230-pound Smith started every game as a freshman, collecting 61 tackles, 6 ½ tackles for loss, three pass breakups, an interception, forced a fumble and recovered a fumble.
Jarron Jones, a 6-5, 305-pound sophomore, took over at nose guard at the end of the regular season and in the bowl game for the Irish after Nix was lost. Jones finished the season with 18 tackles, collecting 11 in the final two games of the season.
Former Bishop Dwenger standout Tony Springmann, who didn't play this season after dislocating his knee in preseason camp, is expected to return and can play either end or nose guard.
Isaac Rochell, who had 10 tackles in five games as a freshman last season, and Chase Hounshell, who missed this season after his third shoulder surgery in two years, will also be in the mix for more playing time.
Jacob Matuska, who didn’t play as a freshman, as well as incoming freshmen Andrew Trumbetti, Matt Dickerson, Jay Hayes, Jhonathon Williams, Jonathan Bonner and Grant Blankenship could also be used on the line.
Linebackers Ishaq Williams, Ben Councell or Romeo Okwara could be moved to end, but that would thin a group looking to replace three starters.
Notre Dame will be making these changes under Brian VonGorder, who replaces Bob Diaco as defensive coordinator, and the Irish will need an experienced secondary to start the season strong behind a revamped front seven.
Notre Dame returns starting cornerback KeiVarae Russell and safeties Mathias Farley, Elijah Shumate, Austin Collinsworth and Max Redfield. All four safeties started this past season, with the freshman Redfield making his first start in the Pinstripe Bowl.
"We've got a lot of young players coming back," Notre Dame coach Brian Kelly said after the 29-16 win over Rutgers in the Pinstripe Bowl on Dec. 28. "So I think it's important for us in the offseason to really develop that continuity and depth on our defense."