CHAPEL HILL, N.C. — Mack Brown has spent 35 years as a major college football coach. He knows what an unacceptable performance looks like. North Carolina’s 70-50 loss to James Madison on Saturday was something, he said, that should never happen. “Embarrassing day, shocking day,” Brown said. “You shouldn’t be at North Carolina and lose to a Group of Five team, period. There are no excuses. Our defense looked awful. We had communication problems, we had missed tackles. We had guys wide open for a touchdown.” Alonza Barnett III threw five touchdown passes in the Dukes’ quick-strike offense to give first-year coach Bob Chesney a signature victory over an Atlantic Coast Conference team. “It can only come back to one person and that’s me,” said the 73-year-old Brown, who won a national title at Texas and is in his second stint at UNC. “I’ve hired everybody on this staff and signed every player on this team. I am at fault 100 percent. I got big shoulders, and I’m embarrassed for our whole program that we would put a product like that on the field.” Barnett threw for 388 yards with no interceptions while also running for 99 yards and two scores for the Dukes (3-0), who had five first-half touchdown drives — four going for five plays or less and three taking less than 35 seconds. James Madison had TDs on offense, defense and special teams in its first victory over North Carolina in four meetings, with its 70 points matching the most ever allowed by the Tar Heels (3-1) in any game as well as the most for JMU against a Bowl Subdivision opponent. The Dukes, who started their now-completed transition to FBS in 2022 and were picked second in their Sun Belt Conference division this season, surpassed their previous-best total against a power-conference foe (36 against Virginia last year) midway through the second quarter. That came on a 39-yard TD pass to Taylor Thompson by Barnett, whose seven touchdowns through the air and on the ground accounted for a school record. “We never stopped believing in our players, they never stopped believing in themselves, and we knew we could win,” Chesney said. “We played harder, we played more disciplined, and we played together and that’s, you know, what I’m most proud of.” The Tar Heels (3-1) yielded a school-record 53 points during a sloppy first half with four turnovers. The bright spots were quarterback Jacolby Criswell, who threw for 475 yards and three touchdowns in his second career start, and running back Omarion Hampton, who rushed for three TDs and 139 yards. James Madison trailed for less than a minute during the game and relied on defense and special teams to take an 11-0 lead in the opening five minutes. After a career-long 50-yard field goal by Noe Ruelas, cornerback Terrence Spence made his seventh career punt block, which was recovered by Jayden Mines for a 14-yard touchdown. Spence also had two first-half interceptions, returning the second 33 yards for a touchdown that put JMU ahead 53-21 at halftime.