One of the biggest reasons for optimism surrounding the New York Giants this year is the fact that their defense will virtually be the same, give or take a spot or two. Linebacker Jonathan Casillas continues to provide a veteran presence but still feels his position group needs to improve.

Casillas has taken on a leadership role since joining the Giants in 2015. He’s viewed as one of the authoritative voices in the locker room, evidential from his role as defensive captain during the 2016 season.

The veteran was a vital piece to one of the strongest defensive units in the league but if they want to improve, Casillas feels the linebackers are the ones who need to step up.

“Our linebackers have to really step up this year and play, if not better, but bigger than we’ve ever played since I’ve been here,” Casillas told reporters on Sunday. “That’s just to keep account with all the guys on the frontend.”

Entering Year 3 under defensive coordinator Steve Spagnuolo, there is more trust between the players and coaches, which is a big reason why the unit was able to allow the second-fewest points per game in 2016, behind only the Super Bowl champion New England Patriots.

As the players begin another season under his defense, they have been given leeway to approach Spagnuolo and the coaching staff with aspects of the scheme that they dislike.

Casillas feels it is one of the reasons the defense is able to succeed so well.

“Spags, I think since his first year to now, I think he’s let his guard down a little bit. He’s let us, as the players, kind of dictate to him in what we like to do and what we’re comfortable with,” Casillas said. “Spags is definitely a guy that, he’s willing to listen to players and even the coaches underneath him to get certain things ironed out.”

Casillas signed a three-year deal with the Giants in 2015, which means this is his final year with the team on that contract. Entering his age-30 season, it will be interesting to see what happens if Casillas has another strong campaign.

As the Giants enter the preseason and regular season, they will do so with the expectation that the defense will continue to be one of the top units. In Casillas’ eyes, the linebacker corps will have a lot to say in that.