In general they should have in-season implications count during the post season.
If you a division rival (not conference) and get 4-0'd during the season then if you both manage to make the play-offs then the team who 4-0'd you only needs 3 wins to advance. Something like that.
If you want to get extreme, maybe whoever wins the match-ups during the season 3-1, would only need to win 3 games during the postseason match-up to advance.