because they've been there done that & if you are truly overpowering a team that means the ball is kept in the attacking 3rd where your d doesn't get any work except in a lightly supportive role, so the experienced coach will instead work the ball around, drops & switches, to goalie & fulbacks, maybe create some drama in the defensive 3rd to keep them sharp, teamwork, skills, communication, etc.
the lessor experienced teams will sometimes take full advantage of lessor opponents & make up for getting squashed the previous week...human nature