It is now trailing Duke by a number of points to begin the season.
On Monday at Wallace Wade Stadium, the Blue Devils shocked the Tigers with a 28-7 victory, continuing the downward trend that Swinney's Clemson has recently suffered.
Clemson struggled in the end zone, was unable to capitalize on Duke's errors, and was outplayed right away.
Nobody but Clemson is to blame for the defeat. After all, the team's possessions in the second half went like this:
Reached Duke's 1-yard line before a blocked field goal
Reached Duke's 7-yard line before losing a fumble
Reached Duke's 1-yard line before losing a fumble
Turnover on downs
Interception
Turnover on downs
Riley Leonard, Duke's quarterback, made enough plays with his arm and legs to gain some separation despite Duke's own mistakes, which included a muffed punt that led to Clemson's lone touchdown and a fumble that was lost in Tiger territory.
He gained 98 yards on the ground in addition to his 175 passing yards, 44 of which came on a dramatic touchdown run to open the second half.
The Blue Devils never looked back after that and may have ruined the Tigers' prospects of winning the national championship before they had a chance to even begin.
In terms of the overall picture, Clemson now appears to be far behind teams like Georgia, Alabama, Michigan, Ohio State, and other national powerhouses. From 2015 through 2019, it hosted four College Football Playoff national championship games, but since then, nothing has remained the same.
In the CFP, the Buckeyes thrashed Swinney's squad, with Justin Fields throwing for six touchdowns as the season's conclusion. Its 2021 season came to an unexpected conclusion in the Cheez-It Bowl, and its 2022 campaign was capped off by a humiliating loss to Tennessee in the Orange Bowl.
After Monday's performance, even making the Orange Bowl this season appears unlikely.