Over the past quarter-century, the running back position has endured many transformations, from the era of the bell-cow back -- at least five carried the football 320 or more times in each season from 1994 to 2006, with a high point of nine in 2003 -- to older backs putting forth unheard-of production -- Tiki Barber (2006), Charlie Garner (2002) and Curtis Martin (2004) all enjoyed 300-point PPR fantasy seasons after turning 30 years old -- to the era of the "committee back" -- there were a combined 51 instances of a 240-carry season from 2013 to 2017, compared to 89 just 10 years earlier, from 2003 to 2007.
Despite those changes, one thing has remained constant in fantasy football: Running back is the position around which to build.
This is especially true in 2018, despite the league's aforementioned shift toward committee backfields, or the rising popularity of fantasy draft strategies like "Zero RB" (which dictates that you roster a minimum of three pass-catchers -- wide receivers or tight ends -- before even considering a running back).
We're in the midst of a youth movement at the running back position, having just completed the greatest season for the freshman running back class in league history, a development bound to expand the gap between the fantasy elite and the replacement level at the position. Pass on one of the top 13 running backs -- and arguably just the top nine -- at your own peril.
Regarding that freshman -- now sophomore -- class, it remains stocked with premium talent, all of which begins the season under the age of 25. Here's a quick look at its 2017 accomplishments:
It was the first rookie running back class in history with as many as four different players scoring at least 220 PPR fantasy points, and the group's collective 7.4 per-game average set a new single-season record.
Alvin Kamara managed the fifth-most PPR fantasy points by any rookie in history (320.4), and his 81 receptions were third most by any rookie running back. He did this despite starting only three games all season, and now he has at least the New Orleans Saints' first four games in which to start, with Mark Ingram suspended.
Kareem Hunt became only the eighth rookie running back in history with at least 1,200 rushing yards, 50 receptions and 10 total touchdowns.
Leonard Fournette became the 39th rookie running back in history with at least 1,000 rushing yards and 10 touchdowns, and he did that in just 13 games, which was tied for the second-fewest played by any of those 39.
Christian McCaffrey caught the fourth-most passes by any rookie running back in history (80).
And let's not forget Dalvin Cook, who at the time of his season-ending injury in Week 4 was ninth at his position in PPR fantasy points (65.4).
Next, consider the strength of the incoming rookie class, which is headlined by Saquon Barkley, who became only the fifth running back in the past quarter-century selected with one of the first two overall picks in the NFL draft when the New York Giants selected him second overall. Barkley's buzz overshadowed what was a relatively deep draft class at the position, one that should further inject youth into the position.
As many as six rookies -- Barkley, Derrius Guice, Rashaad Penny, Ronald Jones, Sony Michel and Royce Freeman -- could find themselves Week 1 starting tailbacks, which would be the most since 2008 (also six), and Kerryon Johnson and Nick Chubb each also has a chance at a starting nod. That's a lot of talent granted a chance to make an immediate impact, certainly as much as we've seen in any other year this decade (besides, obviously, 2017, which still didn't boast that many Week 1 starters).
Now, consider the running backs with two-plus years' NFL experience who won't yet have celebrated their 25th birthdays when the 2018 season begins. Several have generated headlines of their own to this point:
Todd Gurley II, age 24, enjoyed the 20th-best PPR fantasy point total by any running back in history (383.3) in what was a breakthrough third year in the league, and he capped it with what was one of the most dominating fantasy playoff (Weeks 14-17) runs in league history, scoring 123.1 PPR fantasy points during that span.
Ezekiel Elliott, age 23, became only the fourth running back in history to average at least 20 PPR fantasy points per game (minimum 10 played) in each of his first two seasons in the league.
Jordan Howard, age 23, fell just three-tenths of a PPR fantasy point shy of becoming only the 27th running back in history to score at least 200 in each of his first two seasons in the league.
And they're not the only 25-and-under running backs who could play significant roles for their teams. Among the others: Joe Mixon (age 22), Kenyan Drake (24), Derrick Henry (24), Alex Collins (24), Duke Johnson Jr. (24), Tarik Cohen (23), Marlon Mack (22), Jamaal Williams (23) and Aaron Jones (23).
The collective whole of these running backs easily explains why this season, the top 10 being selected from the position have the lowest average age (24.04) this century, more than a full year younger than in any of the previous 17 seasons. That comes on the heels of a 2017 during which the top 10 running backs in PPR fantasy points at year's end averaged 24.48 years of age, the second-youngest this century behind only 2010 -- that was Arian Foster's near-400-point sophomore year, LeSean McCoy's breakthrough year and Peyton Hillis' out-of-nowhere career year.
Remember, it's typically the 24-year-olds who possess the greatest likelihood of a return on your running back investment: Running backs that age have amassed the most 280-point PPR fantasy seasons (an average of 17.5 in a 16-game season) of any age group in history (34), and 25-year-olds are second (33). History says most of the aforementioned players have good chances at either repeating or improving their performances in 2018, which is an astounding prospect.
That helps ease concerns about the most valid criticism of drafting running backs early, that the position comes with the greatest risk of catastrophic injury of any of the four skill positions. In the past 10 seasons, the top 10 running backs selected in ESPN leagues averaged 2.6 games missed, more than the average for tight ends (2.5), quarterbacks (1.8) or wide receivers (1.3).
Narrowing the field to only 25-and-under running backs (a sample of 50), their average number of missed games dropped to 2.2, and for 24-and-under (sample of 33), their average again dropped to 1.9.
A final point in support of the running backs as a whole, which certainly applies to the youthful upper tiers: The position has become far more adept at catching passes in recent years than in the recent past, a boon in PPR leagues, which is where you'll often hear that "Zero RB" strategy suggested. Last season, running backs as a whole caught more passes (2,757) than they did in any of the 14 years that preceded it. The top eight at the position in PPR scoring, predictably, each caught at least 50 passes.
Best yet: Each one of my top seven running backs has caught at least 50 passes in one of the past two seasons, either at the college or pro level. That scoring boost only enhances this group's draft stock compared with the lower-ranked tiers at the position.
Make sure you scoop up one of them early, and if you suffer the misfortune of drawing a lower draft spot, certainly be sure to get one of the top 13 at the position. You're simply not going to find comparable potential in the later rounds, at least not compared to your likelihood of doing so at quarterback, wide receiver or tight end.