In Simple Terms
Traditional Strength of Schedule (SOS) metrics, like those from Massey Ratings, include games against FBS (higher division) and D2 or D3 (lower division) teams. This can distort the picture for FCS teams.
Playing an FBS powerhouse like Georgia might inflate your SOS because they’re strong, but it’s often a guaranteed loss and more about financial payouts than competitive balance. Conversely, a D2 win can suppress your SOS, making your schedule look weaker than it is within FCS.
Followers of FCS, like Sport’s Illustrated’s Zachary McKinnell, have discussed how it can be difficult to rely on SOS rating that are inflated by difficult FBS matchups. Our metric fixes this by ignoring non-FCS games, focusing only on true subdivision matchups for a fairer comparison.
In More Detail
In rating systems based on least squares regression (like Massey’s), game outcomes create a connected graph of teams. Inter-division games anchor FCS ratings to FBS and D2 scales, introducing bias.
FBS opponents, with higher average ratings, boost SOS via large margin losses that “credit” the schedule’s toughness. D2 games do the opposite, pulling ratings down. This variance inflation/deflation skews evaluations—e.g., an FCS team’s SOS might jump 10-20 points from one FBS loss, unrelated to FCS performance.
By restricting to intra-FCS games, our model isolates the subdivision, normalizing ratings around the FCS mean and eliminating external biases.
Addressing Record Impacts and Playoff Implications
Some might argue that non-FCS games already show up as losses or wins on a team’s record, so why worry about SOS distortion? While it’s true that the FCS playoff committee does not penalize teams for FBS losses (considering them “no-harm” scheduling) and does not count D2 wins toward playoff eligibility, relying on a flawed SOS metric that includes these games can still indirectly credit or penalize teams.
For instance, an inflated SOS from FBS blowouts might make a team appear more battle-tested than they are in FCS terms, potentially swaying committee decisions on at-large bids or seeding. Conversely, suppressed SOS from D2 games could undervalue a strong FCS schedule.
Our FCS-only approach ensures the committee (or analysts) has an unbiased tool, avoiding accidental over- or under-crediting based on cross-division artifacts.
Note on Early-Season Variation
In the early part of the season, there is more variation in SOS rankings because some teams have played only a handful of FCS opponents (due to D2 or FBS games in their schedule). This can lead to high variance in the metric, which typically smooths out as more FCS vs. FCS games are played over the season. In this way our metric is also volatile in the early seasons.
It’s true that FBS games make a schedule harder on average, but they likely overrate SOS especially early when data is limited. The inverse is also true for D2 games, which can underrate SOS initially. We created our metric to add more data to the FCS playoff ranking conversation.