CULVER, Ind. -- Has there been a more valuable offseason tool for Notre Dame than the grouptext?

NFL draft pick TJ Jones has mentioned it as a way of keeping in touch with current Irish receivers. Jaylon Smith said in the spring that linebackers past and present kept the conversation going the same way following the 2013 season.

Sure enough this spring, with media members and fans at seemingly every turn asking how the defensive line would replace a pair of NFL draft picks from a season ago, a new position group caught on to the fad.

Junior Sheldon Day led the charge. The only returning starter to what had been the backbone of Notre Dame's defense in recent years had heard enough questions about losing Stephon Tuitt and Louis Nix. Enough that he became fed up, challenging his fellow linemen this offseason.

"I feel like it was the media saying we’re the weak link of this year’s defense -- 'What is the D-line going to do?' And all of this," Day said. "I took it upon myself that I’ve never been that guy where I’m part of the weak link. I refuse to be a part of that. I just kind of reached out to them and said, ‘Do you guys want to be viewed like this? If not, then we need to do this, this, this and this.'"

The early returns have pleased Brian Kelly thus far.

"Our defensive line is a 180 in terms of where they are this year compared to last year, as how they work as a group," the fifth-year Irish coach said. "They have been outstanding and that's led by Sheldon Day. Sheldon Day has been a great leader for us with that group."

Day's emergence as a leader is surprising if for no other reason than his personality, like that of most others, was minimized by the larger-than-life Nix, who went to Houston in the third round of the NFL draft in May. Day laughed when asked if he was just waiting for the nose guard to leave town before showing his true colors.

"It’s not that I was waiting for him to get out of here; I feel like I was just waiting my time," Day said. "Sometimes it’s not appropriate for you to talk if you’re not the older guy or the leader of the D-line."

There is little doubt who leads the unit now, as Day has played 24 games over two seasons, having started during a sophomore campaign that saw him notch 5.5 stops behind the line of scrimmage.

The 6-foot-2, 285-pounder enjoys the simplified approach of moving inside in new coordinator Brian VanGorder's 4-3 front, saying that the defensive linemen get off the ball quicker rather than catching the offensive linemen. To do that, Day dropped five pounds, subbing honey buns and other sugars for high-protein meats and greens.

Of the sacrifice of honey buns, he cracked: "I walk past a Sam’s Club and it hurts my heart."

A pain well worth it, however, in the name of getting a better burst toward the quarterback.

"It was a mutual agreement. I felt like last year I had to gain all that weight to hold the O-linemen and set up the linebackers," Day said. "This year as I’m coming off the ball, I have to be quicker, more explosive. I met with our nutritionist and she helped me come up with a plan and I’ve been following it."