When Bob Elliott was hired as a special assistant to the head coach at Notre Dame, one of his first tasks was to conduct an in-depth study on option football.

Notre Dame plays Navy every year and also had Georgia Tech and Army West Point on the 2015 and 2016 schedules. Elliott, who had previously coached the safeties and linebackers for the Fighting Irish, looked closely at opponents that did a decent job defending the option. He visited those schools, talked to defensive coordinators and compiled a list of strategies that had worked against the unusual attack.

“We did some studies from other programs that had success and wanted to see some thoughts that other programs had that had gone against Navy multiple times and had a modicum of success,” Notre Dame coach Brian Kelly said. “So we kind of compiled all those thoughts and schemes, then sat down and said: ‘What makes sense with what we do?'?”

Elliott, who served as defensive coordinator at Iowa, Kansas State and San Diego State, was charged with installing a scheme designed to stop the option and working with the Notre Dame scout team to prepare those players to operate such an offense effectively.

“I think we've got a pretty good sense at this point of the kind of system of defense we want to play against Navy,” Kelly said. “I think we found a system that we feel is effective.”

Navy's coaching staff can only wonder what that defensive game plan will be. Offensive coordinator Ivin Jasper had developed a feel for the schemes of Brian Van Gorder, who served as Notre Dame defensive coordinator in 2014 and 2015. Kelly fired Van Gorder after a disappointing defeat at the hands of Duke and promoted Greg Hudson to the position.

Jasper has no clue what Hudson, who had been a defensive analyst for the Irish, will want to do against the option. But the Navy staff figures it will be similar to the past two years, since Hudson has been the primary architect of the option schemes.

“It's a new defensive coordinator so it will probably be a new plan. We don't have any idea. We'll go off what we saw last year to try to figure out how they might line up,” Jasper said. “We'll practice against what we think we might see, but we may have to change gears once the game gets going.”

Kelly indicated during his weekly news conference that Notre Dame's safeties will be heavily involved. Starting strong safety Drue Tranquill is the team's second-leading tackler while Devon Studstill is the starting free safety. Nyles Morgan leads the Irish with 67 tackles, and Jasper figures the outside linebacker will also play a prominent role.

Notre Dame has struggled defensively for most of this season and ranks in the middle of the pack among the 128 Football Bowl Subdivision schools in most major categories. The Irish are allowing an average of 28 points (67th) and 388 total yards (54th).

However, the Notre Dame defense has shown improvement of late, limiting North Carolina State and Stanford to 10 and 17 points, respectively. Jasper said the Irish were “playing fast” against Miami, which scored 27 points despite being held to 306 total yards.

“Regardless of the record and stats, they're the Fighting Irish. They're going to be better than us, they're going to be more athletic — bigger, stronger, faster,” Jasper said. “We try to level the playing field with what we do. It's going to be a physical game.”

Kelly is concerned about Navy's triple-option offense, which has been firing on all cylinders of late. The Mids averaged 510 yards and 44.3 points over the past three games — wins against Houston and Memphis along with a loss to South Florida. Starting quarterback Will Worth set a single-game school record for total offense (428 yards) Oct. 28, one week after establishing a career-high for rushing yards (201) against Memphis.

“They just keep rolling offensively. You think they lose Keenan Reynolds and there's going to be drop-off, but Will Worth comes in and picks up where he left off and the production has been unbelievable,” Kelly said.

Kelly believes one key to defending the option is to change fronts over the course of the game.

“If you're going to line up in one front and that's all you do, they're going to get you. They've seen everything and have answers for everything,” Kelly said. “So you've got to show them a few looks. I mean, you've got to move around a little bit. You have a base plan of ‘This is how we're going to defend you.' Then you've got a couple wrinkles off that.”

Kelly also believes it's important to rotate defenders to keep them fresh, and he feels fortunate the Irish have the depth to do so.

“This is a game where we'll have to use more players,” he said. “It's a different game. It's a downhill game and it's a physical game. So we're going to go deep with a lot of players. I think that will probably be the biggest thing we do, is play a lot of players up front.”

Meanwhile, Navy must contend with a Notre Dame offense that has put up big numbers at times this season. Quarterback DeShone Kizer is the trigger man of a passing attack that ranks 35th nationally with 264 yards per game.

Kizer has a pair of dangerous wide receivers in Equanimeous St. Brown and Torii Hunter Jr., who have combined to make 67 catches for 1,091 yards.

“Kizer is a great quarterback with a really strong arm. They have big-time receivers, very good running backs, outstanding tight ends,” Navy defensive coordinator Dale Pehrson said. “Also a very big, athletic offensive line. Every year, I think they're the best-coached offensive line we see.”