Expected Fantasy Points and Fantasy Points Differential

How to analyze the output of an individual player’s season when it comes to fantasy football is a much-discussed topic. Some simply look at the final points total and judge a player based on what the number says at the end of the season compared to expectations at draft time. Meanwhile, other fantasy football GMs will dig into statistics such as passing yards per attempt or yards per target. Here at Pro Football Network, we wanted to develop methods that utilize fantasy points but in a way that gives fantasy football players a number that makes it simple for them to understand how players performed in previous seasons. Those methods are our Consistency Score and Fantasy Points Differential.

What is Fantasy Points Differential?

In its simplest terms, Fantasy Points Differential (FPD) is the percentage difference between a player’s final fantasy point output and their expected fantasy points (xFP). A player’s xFP is calculated based upon their opportunities in that season, using the previous decade’s statistics to identify the elements that derive the most logical trend with fantasy point output.

xFP in essence tells you what an average player would have done with the opportunities seen by any given player in any given season. FPD then tells you how much better or worse that player was in that year compared to an average player.

What does Fantasy Points Differential tell us?

Fantasy Points Differential allows us to examine how a player performed in any given year based on his opportunities. For example, we can see that in 2019, Raheem Mostert performed superbly compared to how an average back with his opportunities would have performed.

Additionally, with slight modifications to the formula, we can utilize FPD in order to judge how a player is performing in season. That ability to examine a player’s performance in season will allow us to identify players to buy-low or sell high on and will serve as the basis for the series of articles identifying those players in 2020.

What are the standard scoring settings for Fantasy Points Differential?

During the development of Fantasy Points Differential, we examined multiple scoring settings; four points per passing touchdown vs. six & non-PPR vs. half-PPR vs. PPR being the main focus. Ultimately, the numbers across the different settings were within similar ballparks and therefore, we chose to go with the current most-standard setting across the world of fantasy football: four points per passing touchdown and PPR.

How is Expected Fantasy Points Calculated?

The calculation of expected fantasy points is different for each position, as the key elements for the production of each position differ. For each position, we correlated fantasy points in a given part of their game with the elements that affected those outputs. For example, for quarterbacks, we calculated fantasy points earned by passing the ball and then looked for a correlation between elements such as passing attempts and passing completions.

In that example, although completions had a stronger overall correlation to fantasy points than attempts, it was apparent as to why completions would correlate more favorably. Therefore, as passing attempts is the logical input factor in the passing game, xFP is calculated using passing attempts.

In short, the following elements were utilized primarily to calculate xFP for the different positions; passing attempts, carries, and targets. The only position to use a different element than one of those three is the impact of the passing game on running backs. As some backs are considered to have been targeted when QBs throw the ball into the ground on blown plays or failed screens, these numbers were unfairly affected for some backs. Therefore, in the xFP equation for running backs, receptions are used to calculate a player’s expected output.