(Leading up to the start of free agency on March 14, Panthers.com is looking at the state of each position group.)

POSITION REVIEW: The Panthers' first line of defense was first-rate again in 2017. Carolina finished the season ranked third in the NFL with 50 sacks and fourth in rush defense, allowing just 88.1 yards per game. The line got some of the glory while also doing plenty of dirty work. Defensive ends Julius Peppers and Mario Addison with 11 sacks apiece made the Panthers one of just three teams with a double-digit duo, while Kawann Short and his fellow defensive tackles helped put linebacker Luke Kuechly in position to earn All-Pro honors for the fourth time in his career.

STATS OF SIGNIFICANCE: There has been turnover along the line in the past and probably will be again, but this unit under line-coach-turned-coordinator Eric Washington has excelled over time. Beginning with the 2012 season, Carolina's 219 sacks by defensive linemen lead the league by 21, and the Panthers rank third over that time frame with just 96.2 rushing yards allowed per game.

WORTH WATCHING AGAIN: In Week 8 at the Buccaneers, Peppers made history when he got to quarterback Jameis Winston for the 151st sack of his career, moving him into fourth in NFL history. Peppers also forced a fumble on the play – something he's done 49 times in his career.

TOP OFFSEASON STORYLINES: The staying power of the Panthers' defensive line will be tested again in 2018. While hopes run high that Peppers will opt to return for a 17th season, there's a good chance this will be the end of the line in Carolina for space-eating defensive tackle Star Lotulelei, the Panthers' first-round pick in 2013. With or without Peppers or Lotulelei, the Panthers could use a shot of youth in the form of someone like Daeshon Hall on the outside or Vernon Butler on the inside. And, of course, there's the draft.

HOPE FOR 2018: At the very least, Carolina will need a new rotation piece at defensive end with the departure of Charles Johnson. And with Peppers close to the end and Addison now in his thirties, the draft might be the way to go. Marcus Davenport of the University of Texas at San Antonio, Arden Key of LSU and Sam Hubbard of Ohio State have been identified in mock drafts as possible Panthers' first-round targets, but maybe there's a chance of one them could last until Carolina selects in the second round at No. 55.

The Panthers seem less likely to invest an early draft pick at defensive tackle (never say never), but the draft class appears to be pretty deep. Of note, N.C. State just down the road has three defensive tackles that can help somebody – B.J. Hill, Justin Jones and Kentavius Street.