Manny Diaz probably doesn't get enough credit for the job he's done with Duke football, at least from the national side of things. He's certainly well thought of in Durham, and Duke AD Nina King rewarded him with a contract extension this offseason after back-to-back nine-win seasons and the program's first outright ACC Championship since 1962.
Despite that track record of success, most expect the Blue Devils to take a significant step back in 2026 after the transfer departure of QB Darian Mensah. That, of course, ignores the fact that Duke won nine games the season before Mensah arrived in the Bull City.
Mensah's late departure was obviously problematic, and Duke was left with limited Transfer Portal options. They landed Walker Eget from San Jose State, who threw for over 3000 yards last season, but he won't have the same ceiling as Mensah. Nor will redshirt freshman Dan Mahan, who is competing with Eget for the starting job.
But that might not matter.
Duke's offense will look different next season, but that doesn't mean it has to take a step backward. Rising sophomore Nate Sheppard should be one of the nation's top running backs after a phenomenal freshman season that saw him eclipse 1100 rushing yards. Duke's offensive line could be a strength, too, with two returning starters and the addition of All-Sun Belt tackle Nick Del Grande from Coastal Carolina. The ground game will be the strength, and if either Eget or Mahan can limit mistakes and effectively manage the game, Duke's offense might not take a step back next season.
The real key will be Diaz fixing his defense, which finished last season ranked 86th in SP+.
ESPN's Bill Connelly noted in his 2026 ACC preview that Diaz has found success despite not putting everything together at the same time:
Bill Connelly believes Duke has a higher ceiling under Manny Diaz than we've seen so far
"If you put Duke's 2025 offense, 2024 defense and 2025 special teams unit together, you would have a top-20 team, per SP+. If you put the other team together -- 2024 offense, 2025 defense, 2024 special teams -- you'd barely have a top-80 team," Connelly writes. "Diaz's first two seasons at Duke have produced a good version of everything. They've also produced a pair of nine-win seasons and an ACC title. Now just imagine what could happen if Duke does all the good things at the same time."
Duke finished 19th in the country in SP+ offensively in 2025. It's fair to expect some slippage based on QB play, but again, the Blue Devils may make up for that with an even more dynamic ground game. And whoever starts at QB will have the benefit of some talented receivers, even with Cooper Barkate joining Mensah in Coral Gables. Transfers Jared Richardson (Penn) and Javen Nichols (Charlotte) will join a talented crop of youngsters split out wide for Duke.
Diaz's biggest challenge will be getting his defense back toward 2024 levels. The Blue Devils slipped significantly in 2025, particularly on the back end.
Per Game on Paper, Duke ranked 135th out of 136 FBS programs in Total EPA against the pass. They ranked 124th in success rate. Unfortunately, Duke also lost its best player in the secondary to the draft in Chandler Rivers, who became a fifth-round pick by the Baltimore Ravens.
Perhaps natural growth will help in the secondary. Duke was young on the back end, and Diaz has had success with player development on that side of the ball throughout his coaching career. He also added a pair of transfer corners in Che Ojarikre from Stanford and Dylan Flowers from Western Kentucky, who could pay immediate dividends.
If Duke can find a way to maintain a Top 25-30 offense while pairing that with a Top 25-30 defense, then the Blue Devils might find themselves even better in 2026 without Mensah than they were with him in 2025.
If the offense takes a slide, however, and the defense doesn't take a step forward, then the downturn that most experts believe is inevitable might just come true.
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