Last week I published my pre-draft quantitative models predicting fantasy success for running backs and wide receivers. A key variable in that analysis was draft position, for which I used expected draft position based on recent mock drafts in lieu of actual draft positions. We have the actual draft positions now that the draft is complete, and with those I can update the model results for the 2021 class with more accurate results.
In this analysis of 2021 NFL draft prospects at the wide receiver position, I’m going to detail the quantitative process behind the results, including the importance of different features and how measurables, workout metrics and production markers all blend into a single prediction. In this case, the prediction will be focused on fantasy results, specifically the number of top-12 weekly finishes at the position over the prospect's first three NFL seasons. We could extend the window further to cover a player’s entire career, but the point in the real NFL draft and the fantasy rookie counterparts is to see a return on investment earlier rather than later.
This analysis will cover all drafted wide receivers from the 2021 class, plus a couple undrafted free agents who were fairly high on the PFF Top-300 Big Board, using their pro day number and production metrics to forecast fantasy success.
This analysis uses what is known as an ensemble model, or a blend of the results from different models which are then blended together to form a single, and hopefully more precise, final prediction. One of the models is tree-based, the other linear. The historical data from previous wide receiver classes going back to 2006 and through 2018 were used to train the models, including the number of actual top-12 weekly fantasy finishes for those previously drafted wide receivers. The historical fantasy finishes are based on points-per-reception (PPR) scoring.
The features for each wide receiver in the models are as follows, ordered by relative importance and statistical significance. The stats are from the prospects’ best statistical season in which they played at least five games and logged at least 25 targets:
- Draft position
- Career market share of team receiving yards
- Yards per route run
- Best-season market share of team receiving yards
- Career market share of team receiving touchdowns
- 40-yard dash
Draft position is the most important feature in predicting fantasy success for wide receivers, followed by production and then measurables. Workout metrics in the model were limited to the 40-yard dash due to its ubiquity and outsized influence on NFL draft position for wide receivers. For the 2021 class, the 40-yard dash times are from pro days, with a 0.03 penalty for comparison to combine times. For the few wide receivers without pro day times, I estimated the times based on media reports and built in conservatism.
Higher drafted wide receivers at top programs are more often coming from receiving groups with two, three and even four drafted players, thereby diluting their shares of team production having to split workloads. To account for this, I adjusted up the career shares of team receiving yards and touchdowns for wide receivers by the number of wide receivers drafted in the top-100 picks that they played with during their careers.