How much you win a game by has no bearing on power points. The strength of your opponent, i.e., the numbers of games they win over the course of the season, does factor into your team's rating because you get 2 bonus points for each of your opponent's wins if you defeated them; one point for each of their wins if you lost to them.
What the Post is saying about "Briar Woods remains in the playoff field due its strength of schedule" is referring to the fact that they will get more bonus points from playing stronger teams and their opponents' wins that may elevate their overall standing. In terms of just bonus points, it is better to lose to three teams that go 10-0, 9-1, 8-2 than it is to beat three teams that go 3-7, 5-5, and 4-6. In this example BW would get 27 (10+9+8 times 1 point per opponent win) bonus points from the three good schools they lost to, whereas they would get only 24 (3+5+4 times 2 points per opponent win) bonus points from the teams they defeated. That effectively means their final average in the first scenario will be 0.3 points higher than the second scenario (27-24 divided by 10 games for the season = 0.3). 0.3 extra from the bonus points can be enough to get into that last playoff spot.
Keep in mind that this is only for bonus points. Power points for wins/losses are more complicated and also could have a factor for division the opponent plays in, as well as if they are in your conference or not. It is complicated.
