Jon Moore

Fantasy Fallout

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NFL Draft: The Phenom Index

Thursday, March 27, 2014

In the distant corners of your sports memory, does the name Danny Almonte ring a bell?  He was the kid who struck out 16 en route to a perfect game in the 2001 Little League World Series.  The trouble with Danny, however, was that his father forged his birth certificate to sneak him under the tournament’s age limit.  Instead of being a 12-year-old phenom, he was a 14-year-old padding his stats against younger kids. Of course he was dominant!  I share this story as a reminder that age does matter.  It’s the reason there are birthday cutoffs for junior sports, but, for some reason, we seem to forget that fact when it comes to NFL prospects.


Consider that most people graduate from high school and enter college sometime around their 18th birthday.  When accounting for a possible redshirt year, this means that the vast majority of college football players are between 18 and 23 years old, with the average starter being somewhere around 21 or 22.  Based on this information, what type of player would you choose, a 23-year-old who dominated or a 19-year-old who dominated?  The answer is clear -- the 19-year-old -- but there hasn’t been a good way to incorporate that directly into the stats, which is why I created the Phenom Index.


The Phenom Index is my way of adjusting production based on how old a prospect is when they produce it.  It works for several fantasy football relevant positions, but for this article, we’ll be focusing on wide receivers.  To calculate the index, we need two variables from a player’s final college season: age and production.  For age, it’s just how old they are on December 31 of their final year.  For production, we use Dominator Rating (DR), which was coined by Shawn Siegele.  If you’re not familiar, DR summarizes the percentage of a passing offense for which a player is responsible.  So, if a receiver caught 1,000 yards of a possible 2,000 his DR would be 50%.  I use this instead of raw stats because it doesn’t care if a player comes from an option offense or a 5-wide scheme; it just looks at how dominant they were relative to their opportunities.  The numbers look something like this:


Final Season Dominator Rating


45%- amazing

35%- above average

25%- average

15%- below average

5%- poor


Final Season Age for Draft Eligibles


24.5- old

23.5- older

22.5- average

21.5- younger

20.5- young



All we’re doing now is comparing their production to their age.  Since these numbers are on different scales, I standardize them before I divide them, but the Phenom Index is basically just:


Dominator Rating




If a player had exactly average production and was the exact average age their score would be 1, which always represents average production for any age.  To have a high Phenom Index score means a player had high production and a lower age; a bad score would mean low production and higher age.  Let’s look at a real life example from the 2010 NFL Draft.





It’s almost comical to think about now, but Jordan Shipley went three picks ahead of Eric Decker in the 2010 Draft.  Shipley did have above-average production, but he was such an old prospect that his score was 6% below his age-expectation (.94 minus 1).  We could speculate that Decker slid because of his pre-draft foot injury, but based on this metric, he was a far superior prospect and has delivered superior results.  So, how much can the Phenom Index tell us about a player?


In a test of more than 300 receivers from 2006-2011, the Phenom Index alone explained 23% of variance in fantasy output over a player’s first three NFL seasons.  When combined with draft position it explained 46% of variance.  Without ever watching a minute of film, looking at a player’s 40 time or knowing how tall they are, the Phenom Index helps us predict 46% of a player’s fantasy football success.  For perspective, predicting 100% would mean that you and Michael J. Fox just got back from the future and know how everything will unfold.


To see how this translates into today’s NFL, I’ve included the following tables, which show the best and worst scores for players drafted in the top 100 picks (2006-2013).  I chose this cutoff because these guys were taken with valuable picks and expected to receive playing time.  The first list is the younger guys who played far above their age-expectation and, to be clear, this is the complete list—no cherry picking.





For Josh Gordon, his final season at Baylor yielded average production, but because he was three years younger than average (19.7 compared to 22.5) his score is through the roof!  Then consider his great physical attributes and strong rookie year performance and it’s no wonder he exploded in 2013.  Interpreting the numbers, he was more than 3 times better than his age expectation (4.48 minus 1), indicative of a high-caliber prospect.  Another 2013 breakout, Keenan Allen, was nearly 2 times better than his age expectation.  Like Eric Decker, Allen fell to the third round because of injury concerns, but the precocious talent was obviously there.  Overall, 30% of this top cohort have posted WR1 seasons and more than half have posted a top-25 fantasy season.  I think at least three more (Hopkins, Hill, Randle) will do so before their careers are over.  Scoff at Dwayne Jarrett if you must, but alcohol-related issues derailed his career and there’s no way to know about personal issues without access to these players. 


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