Campbell, returning from a year off, had what Sullivan termed a "frustrating" time in his first game since the 1990-91 season.
Picking up three fouls early in the first half, Campbell was forced to play cautiously for the rest of the contest.
Still, he picked up eight points and seven assists while controlling a Crimson team which seemed surprisingly in-synch for the first game of the season.
Walker, who ended with 25 points, picked up on this cohesiveness in his sky-view assessment of the Crimson.
"If the first game is any indication, [Harvard] is a lot better than last year," he said. "They don't really have the same kind of talent, but they seemed to play a lot better as a team."
Sullivan said he saw a "lot of positives in the game, but we also have a lot of things to work on. Holy Cross is as good of a team as we'll play this year. Based on that, I don't think we did too bad."