CLEMSON, S.C. (AP) Clemson linebacker Isaiah Simmons accepts that many are concerned over the Tigers changing defense from its latest national championship. He's not among them.

The 6-foot-4 junior is supremely confident Clemson will excel despite losing seven starters - including its NFL-ready defensive line - from its historic 15-0 title season a year ago. "There can't be a drop-off," said Simmons, Clemson's leading tackler. "We won't allow it."

It will take more than sheer will for the Tigers to play as strongly on defense as they did last season. Three of its draft eligible linemen - ends Clelin Ferrell and Austin Bryant and tackle Christian Wilkins - all passed up the NFL to return for a final college season in 2018. Ferrell and Wilkins were AP All-Americans this season, combining for 17 sacks and 34.5 stops behind the line. Also gone is tackle Dexter Lawrence, championship game MVP in cornerback Trayvon Mullen and linebackers Tre Lamar and Kendall Joseph. Many of those players will hear their names called at the NFL draft later this month.