Sortino Ratio: A New Floor/Ceiling Combo Metric

In fantasy football, there are tons of different metrics that we use to help us evaluate players. But despite the laundry list of tools available to fantasy football analysts, we don't have a simple measure of a player’s floor/ceiling combo.

Other analysts have made attempts to quantify the impact a player's scoring distribution has on our fantasy teams. Michael Dubner developed a metric he dubbed "Functional Fantasy Points" (essentially points above replacement).

Hayden Winks took a similar approach, utilizing points above replacement as well, in order to evaluate which players were "better in best ball."

Points above replacement can be a great metric to use in certain circumstances; however, it has a blind spot for players that deliver a few big spike weeks but then bust either frequently or catastrophically... or both. In summary, points above replacement doesn't really care about your floor.

As much as I generally advocate for focusing on ceiling for best ball teams, we need to find the fine line between a team that is entirely boom/bust and a team that puts up solid weekly scores with access to tournament-winning upside when it counts.

So, I borrowed a metric that is commonly used in finance and translated it to fantasy football.

Introducing the Sortino ratio

Sortino ratio is similar to the more widely known Sharpe ratio, but the Sortino ratio does not punish assets for deviating to the upside. We like upside around here.

To put it in fantasy football context, the players are our assets, and their weekly fantasy points are our returns. We’ll be looking at their points above a replacement level (using the replacement level as our risk free rate) and dividing by their downside deviation.

Practical Applications

What can we take away from a player’s Sortino ratio?

This is a descriptive statistic that helps us to quantify how often and the magnitude with which a player scored above or below replacement level.

What Sortino ratio cannot do is predict future performance any more than historical fantasy production predicts future performance.

Instead, it can inform us as to what type of scoring distribution a player might have based on the situation and circumstances from prior years. If a player has a major change in their situation, continues to develop as a player, sees a decline in production due to age, etc., their historical Sortino ratio may not be at all indicative of how their fantasy points will be distributed given their new situation.

To explain the Sortino ratio in a nutshell, it’s a metric that can capture a player’s floor/ceiling combo in one neat number. Players with a high Sortino ratio aren't boom/bust. They boom more often (or boom bigger) and bust less frequently (or less severely). So, when comparing two players who we expect to score similar fantasy points, we would typically prefer the player with the higher Sortino ratio.

As you would expect, there is a high correlation between fantasy points per game versus Sortino ratio. However, there are times when Sortino ratio deviates from fantasy points per game. Those instances can be very enlightening as to the scoring distributions of specific players. Here is an example from 2023 RB scoring: