Last year, Ohio State was the best serving team in the nation and perhaps the best passing team in the nation. Even if BYU had served more aggressively in that match it probably wouldn't have made much of a difference.
Where BYU needed to improve, and still needs to improve, is in serve receive, overall passing, and ball control. There was a lot of talk last year even before the championship game about BYU's struggles in these areas especially against strong serving teams like UCLA. BYU survived for a while, but it caught up to them against Ohio State.