The model incorporates numerous factors, including three (expected points contributed by offense; simple rating system, or SRS; and offense simple rating system, or OSRS) used by Pro Football Reference to measure teams' offensive efficiency and quality. The expected points statistic reflects the fact that all yards are not created equal, illustrating which teams are able to make the most of their offensive opportunities. That is, a 12-yard gain on third-and-20 adds more to a team's yardage total than a 3-yard gain on third-and-1, but the latter play is more valuable. This measurement is meant to account for that difference. The simple rating system statistics are a measure of a team's caliber relative to the league average, based on margin of victory and strength of schedule. The model also rewards wins and penalizes teams that punt or turn the ball over frequently. In other words, teams that are efficient on offense, play well against tough opponents, and take care of the football will rate higher than those that don't.