Campbell hasn't played a full 90 for quite a while, mainly due to his fitness/injuries over the last few years.
60-70 minutes is what we usually get out of him and he manages to keep himself fit doing it.
Sometimes it's just better with a player like Campbell to not risk them for 90 minutes and potentially get them injured.
He's already missed quite a few games at the mid point of the season (late November to early January) with what was apparently a back injury, during that time we rotated between Moore, Brewster and Oné.
Maybe in preseason we might be able to get Campbell up to full 90 fitness, Ndiaye didn't often play the full 90 minutes in that first season he had with us, whereas in his second season he did 90 minutes most games.
Moore started the season playing 90 minutes nearly every game, and eventually it caught up to him where he had 2 lengthy spells on the sidelines (1st with injury, 2nd for his surgery).