Ehrhoff had less points on a vastly better team. Plus/minus is a negligible stat for judging them because of the two teams positions. Ehrhoff's plus/minus was solely because of the higher scoring offense in front of him and the goalie behind him. Kaberle's was the lack of both previous mentioned reasons.
Kaberle passing to the Sedins is a whole ton better than Ehrhoff to the Sedins.