Per ESPN:

The reason for the change was because three of the four remaining Power 5 leagues (Big 12, Pac-12 and Big Ten) play nine conference games or will be going to nine conference games, meaning fewer nonconference opportunities, a source said. Also, the ACC believes games against BYU -- which has gone to 10 consecutive bowl games under coach Bronco Mendenhall -- would help the league's overall strength of schedule, a source said.

Beginning in 2016, the SEC also will require its league members to play at least one nonleague Power 5 team. Last year the SEC said BYU would not count toward the SEC's requirement. An SEC spokesman said Thursday the SEC's stance toward BYU had not changed.