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In 2015, I had a hypothesis. Point per reception scoring, or PPR, was designed for redraft leagues to bring wide receiver values into rough parity with running back values on a year-to-year basis. Wide receivers have longer careers than running backs, though, so their value was already in rough parity in dynasty leagues. As a result, I believed, using PPR scoring in a dynasty league would tilt the field too much towards wide receivers.

Like any good hypothesis, there was only one thing for me to do: try my best to prove it wrong. So I compared career fantasy value (as measured by EVoB, my own pet all-in-one value metric) to career NFL value (as measured by AV, or approximate value, a metric developed by www.pro-football-reference.com to estimate a player's contributions to his team). If my hypothesis was correct, receivers should average more EVoB per point of AV— more fantasy value per unit of NFL value— than running backs.

My hypothesis... was not correct. In fact, PPR scoring brought running back and wide receiver value into near-perfect parity, (though it murdered quarterback value in the process). In fact, if I set out to engineer a system, no matter how complex, that valued running backs as closely to wide receivers based on their contributions on the field I doubt I'd be able to do a better job.

So that was the big takeaway from a conceptual standpoint in 2015: assuming equal quality, running backs and wide receivers are equally valuable in PPR scoring. But the practical consensus of the day was markedly different: ignore running backs, build around wide receivers.

How can one person demonstrate that the positions are equal while everyone else is convinced they're markedly unequal? Like most things in dynasty, it's all about the talent.

When All Else Isn't Equal

Remember my initial finding: assuming equal quality, running backs and wide receivers are equally valuable. From 2009-2014, however, we were not given equal quality. The top running backs drafted between 2009 and 2014, as measured by AV, were LeSean McCoy, DeMarco Murray, Le'Veon Bell, Ryan Matthews, Mark Ingram, Eddie Lacy, C.J. Spiller, Doug Martin, Knowshon Moreno, and Rashad Jennings.

(Approximate Value is a volume stat and, as such, is biased towards players drafted earlier who have had more seasons to accumulate value. Devonta Freeman and Giovani Bernard will probably supplant Moreno and Jennings in the next few years.)

Now, that same list for wide receivers: Antonio Brown, Julio Jones, Demaryius Thomas, A.J. Green, Dez Bryant, Mike Wallace, T.Y. Hilton, Jeremy Maclin, Randall Cobb, Michael Crabtree. Again, later drafted receivers haven't had a chance to accumulate much value yet, so players like Odell Beckham, DeAndre Hopkins, Mike Evans, Jarvis Landry, Brandin Cooks, Alshon Jeffery, Keenan Allen, Sammy Watkins, Allen Robinson, and Davante Adams will continue to climb this leaderboard.

Over that six-year span, there were four drafted running backs with a career AV of 40 or more. There were twelve backs with an AV of 30 or more, and there are just twenty-one running backs who have an AV of 15 or higher and who were still active in 2017.

For wide receivers, that's sixteen players with a career AV of 40 or more, twenty-three with a career AV of 30 or more, and forty-nine who have a career AV of 15 or higher and were still active in 2017. It's a ludicrous talent disparity; the wide receivers who entered the league from 2009 to 2014 were miles better, as a whole, than the running backs during that span.

(As an aside, based on the draft capital spent at each position, NFL decision-makers knew it. There were thirty-six wide receivers drafted in the top 50 picks during those years compared to just fourteen running backs.)

Given that talent disparity, it makes sense that everyone thought that receivers were the One True Path to Success(TM). Remember, fantasy value is highly correlated with AV, and wide receivers dominated AV. But fantasy is a forward-looking hobby, not a backward-looking one; in 2015, we no longer got points for what receivers did in 2012. The important question at the time was “is this massive disparity in incoming talent structural or temporary”.

In favor of the “structural” argument was long-term NFL trends. The league had been throwing more and more passes and calling fewer and fewer runs since 2004, a trend that started accelerating in 2011.

But this is something of a circular argument; was the league calling more passes and fewer runs because there were more good wide receivers and fewer good running backs? If so, as soon as some quality prospects started to enter the league, we'd see those trends slow or even reverse.

Indeed, the past three draft classes have included a bumper crop of quality running back prospects, and those league-wide trends towards the pass have slowed and in some cases even reversed. It seems that the incoming talent disparity was temporary after all.

A tool I like to use to measure how much young talent there is in the league at a given position is “fantasy-point-weighted age”. It's the average age of every player at a position in the league, weighted by how many fantasy points they score. As a result, Todd Gurley (279.7 points, age 23) contributes much more to the average than, say, Frank Gore (118.9 points, age 34).

If a lot of good talent enters the league, that good talent will displace existing veteran talent and skew the age younger. If there's little incoming talent, then the veteran talent maintains its hold on the production, ages a year, and the average age skews older.

I first looked at production-weighted age back in 2013 to note how dire the situation was at running back. I revisited in 2015 to note that the situation wasn't improving at running back, but that wide receiver was undergoing a renaissance.

Both times I advanced the hypothesis that this disparity was transient and that random fluctuations in incoming talent would even out going forward. And like all of my hypotheses, I'm going to revisit it and attempt to prove it wrong. So here's the production-weighted average age at the running back position for the past decade.

I love it when a good hypothesis stands up to scrutiny. (I love it when a bad hypothesis fails scrutiny, too, because it means I can jettison it to stop believing wrong things and start believing right things instead.)

From 2008 to 2010, we saw the effects of the stellar 2008 class of running backs, (plus Adrian Peterson and Marshawn Lynch from 2007). They dominated the position and kept the average age low. But by 2011 we started to see the lack of incoming talent, as average age rose by more than a full year and stayed high for the next five.

The last two times I wrote about this (2013 and 2015), not coincidentally, were the only two times this past decade that average production-weighted age for running backs surpassed 26 years. Backs were either young or backs were productive; very few backs were both at the same time.

But what's happened in the last two years? A flood of incoming talent has happened. Seven of the top ten backs in fantasy football this year were drafted since 2015: Todd Gurley, Kareem Hunt, Alvin Kamara, Melvin Gordon, Leonard Fournette, Jordan Howard, and Ezekiel Elliott.

Meanwhile, only one of the top ten wide receivers— Tyreek Hill— entered the league in the last three years. You'd have to go all the way down to Juju Smith-Schuster at WR31 in order to find seven receivers from the last three classes, (Stefon Diggs and Devin Funchess from 2015; Tyreek Hill, Michael Thomas, and Robby Anderson from 2016; and Cooper Kupp and Juju Smith-Schuster from 2017).

It turns out that investing heavily in the wide receiver position was not the panacea it was once seen as. No, the players dynasty owners should concern themselves with investing in are the good ones; given talent, position is largely irrelevant.