Easiest way to think of it is that quality wins count for you, quality losses don't hurt you.

By that measure a team like Georgia instead of being 5-2 (victories against Arkansas, Auburn, Tennessee, Kentucky, Miss St and losses to Alabama and Florida) is viewed by the committee as 1.5-0 having beat Auburn and an at-the-time highly regarded Tennessee, whereas BYU is 0.5-0 having only beaten a generally good (but still G5) Boise St team.

All the other wins and (for Georgia) losses make some adjustment at the margins, but that's the starting point from the committee perspective.