At the end of every fantasy season, I like to look at the year that was in a historical context, attempting to pinpoint statistical outliers that should regress to the mean in the following season and to isolate league-wide trends that might help us in projecting what will happen the following year. 2017, of course, is no exception.

Step-by-step, I’ll walk you through my methodology by highlighting the data I find most relevant, while also noting what I see as the major takeaways.

First, I looked at league-wide rushing and passing statistics since 2000.

Rushing/Passing Stats Since 2000 pic.twitter.com/YuTn4DlZdG — Scott Barrett (@ScottBarrettDFB) February 7, 2018

You'll notice that rushing production and efficiency was at or near 18-year lows, but still well in line with the three-year trailing average. Conversely, pass attempts were at the high-end of the spectrum (in our sample), but still below average in recent seasons. Much of this decline (in contrast to the more recent trend), as well as passing efficiency lows, can be explained away by key injuries to top-tier quarterbacks in Aaron Rodgers, Andrew Luck, and Carson Palmer. Still, there’s a clear trend of teams passing at a much higher rate since 2011, which also coincides with the NFL's incorporation of the defenseless receiver rule. In 2018, I’d expect passing volume to rebound and stay in line with our more-recent trend.

We can dig even deeper into this data by splitting these statistics by position.

Looking at the quarterback numbers, everything seems in line with our assumptions in the previous paragraph, but one interesting development to note is the new decade-high in every rushing metric. Cam Newton, Tyrod Taylor, Deshaun Watson, Russell Wilson, DeShone Kizer, and Carson Wentz (in order) led all quarterbacks in rush attempts per dropback last season. Rather than indicating the start to a new league-wide trend, I’d expect these numbers to decline closer to our sample’s average rate in 2018. Taylor and Kizer aren’t guaranteed starting jobs next year, and the Texans and Eagles may be more inclined to preserve the health of their franchise quarterbacks by asking them to run less frequently next season.

Running backs were underwhelming in rushing production, but this was also in line with their trailing four-year average, and they more than made up for this decline via production as receivers – hitting new highs in every receiving metric. I'll expand on this a little bit later, but I do see this as part of a new league-wide trend, and something we'll need to embrace for fantasy purposes.

Wide receivers had, easily, their worst season (by almost every metric) since 2011. In part this could be due to the quarterback injuries mentioned elsewhere, but also injuries to players like Odell Beckham Jr., Allen Robinson, Julian Edelman, and more. Though, I do think, and will expand on later, that they were somewhat hurt by the newfound rise of the pass-catching back.

Tight ends, interestingly, saw a new high in average depth of target, while all other metrics hovered around our sample's average. Like with wide receivers, I can't help but wonder if running backs are to blame. Perhaps in 2017, running backs assumed more of the “safety valve” role that was also commonly held by tight ends, forcing quarterbacks to target tight ends deeper down the field. Like with the wide receivers, the tight ends were also hurt by injuries to quarterbacks and to frequent leaders in fantasy points per game like Jordan Reed, Greg Olsen, and Tyler Eifert.

Again, we can dig even deeper into these numbers by looking at raw fantasy production at various positional rankings over the past 10 seasons.

Full Season (Total Points) Fantasy Production (2006-2017)by Position, Split by End of Season Positional Rank pic.twitter.com/4CcRhQt9RG — Scott Barrett (@ScottBarrettDFB) February 7, 2018

You'll notice again how historically poor this season was for wide receivers. The chart highlighting running backs shows what we know intuitively to be true – there's not much value in the RB2-or-later range, but top-flight bell-cow running backs are frequently your league-winners. For quarterbacks and tight ends, you'll see there's not much differentiation after the top player at each position, fitting with the long-held belief that it better to “wait on” these respective positions when drafting.

However, even at the high ends of the spectrum, production suffered. Russell Wilson was the only quarterback in 2017 to post a top-35 fantasy season by a quarterback over the past decade. Only one wide receiver ranked top-30 in raw targets (DeAndre Hopkins) or top-20 in raw fantasy points (Antonio Brown). No tight end ranked within the top-15 in fantasy points or top-25 in targets. Running backs, meanwhile, fared slightly better – five performances in the top-35 in fantasy points and, interestingly, five top-15 finishes in receiving yards.

Finally, I’d like to steer you toward this chart (and thread) that splits each position even further (again by positional ranking).

2017 Fantasy Points Split by Positional Grouping Notes: What a crazy bad year for WRs pic.twitter.com/KAIrX0vUjK — Scott Barrett (@ScottBarrettDFB) January 2, 2018

This chart, more so than the others, does a tremendous job of highlighting just how underwhelming this fantasy season was in terms of raw points, and especially for wide receivers, TE1s, and RB2s.

WR1s, WR2s, and WR3s all hit decade-lows in fantasy production. By any measure, this was a disastrous year for the position. The question then becomes, is this just a one-off outlier, or is this a new statistical trend? I wanted to explain this away by citing quarterback injuries, but these numbers are so glaring that it’s possible there is a second and potentially more impactful culprit.

My hypothesis is this: in 2017, teams used running backs as an extension of the passing game more frequently, and to the detriment of wide receivers for fantasy. Indeed, the numbers back this up.

I think @LordReebs beat me too it, but I found the likely culprit. Substantial uptick for RBs in routes run, routes run as WRs, targets, and air yards. pic.twitter.com/TYuWYMbnNA — Scott Barrett (@ScottBarrettDFB) January 5, 2018

In 2017, running backs hit new highs in routes run, percentage of routes run, routes run as a wide receiver, and percentage of routes run as a wide receiver, though wide receiver numbers were still high here, so this must not give the full explanation.

In terms of targets, target market share, air yards, and air yardage market share, the difference is far more drastic. Compared to their trailing five-year averages, in 2017, wide receiver air yards declined by 5.7 percent and wide receiver targets declined by 7.2 percent. Meanwhile, running backs saw an 8.9 percent increase in targets and a whopping 51.7 percent increase in air yards. By target market share, wide receivers saw a 2.3 percent drop, correlating with an increase of 2.4 percent for running backs.

In PPR leagues, this trend of an increased role in the passing game is still more than making up for their declines in the rushing game that we highlighted earlier. With a new influx of some exceptional receiving running backs in Christian McCaffrey and Alvin Kamara, as well as some well-known mainstays (Le'Veon Bell, Theo Riddick, Duke Johnson, and Melvin Gordon), and some top-tier running backs assuming a new and more robust role in the passing game (Todd Gurley and Carlos Hyde), this helped create this perfect storm of running back receiving production, even in a year we lost the prior season’s running back target leader (David Johnson). It's hard to imagine this trend declines too much in 2018, in another stacked rookie running back class, and after teams take notice of how much of an impact increasing Gurley's receiving workload had on the Rams' offense in 2017. Other statistical studies have also confirmed teams should be using running backs more frequently in the passing game, and especially on earlier downs.

If there’s a key takeaway, it’s one I’ve long argued for. I don’t see the “Zero RB” strategy as a winning strategy. Indeed, the year it gained popularity, was following a massive (and the only) outlier year in terms of running back production.

The running back position is still a risky investment (high bust rate and injury risk), but is also the position where we typically find the highest end of fantasy production that swings leagues. Excluding quarterbacks, 15 of the top 20 fantasy point per game seasons since 2006 have come from running backs, as well as 20 of the top 30.

With the running back position, I’ll continue the strategy that I’ve long used to great success – targeting the league’s “bell-cow running backs” who are most likely to be used in an every-down capacity and in both phases of the offense, while mostly neglecting more one-dimensional running backs. In 2017, not even including rushing production, Alvin Kamara, Todd Gurley, Christian McCaffrey, Le'Veon Bell, and Duke Johnson Jr. all would have finished as WR3s or better in receiving fantasy points. Last season, excluding quarterbacks and tight ends, 10 of the top-15 highest-scoring fantasy players were running backs. Fantasy’s highest-scoring player, Gurley, scored a whopping 3.7 fantasy points per game more than the top wide receiver.

I would caution, however, I don’t think this means we should over-react to this trend and adopt a “Zero WR” strategy. Wide receiver production should regress positively if only due to the anticipated returns of Andrew Luck, Aaron Rodgers, and Deshaun Watson. Furthermore, true every-down running backs are still a rarity and oftentimes hard to spot (few took Sean McVay at his word that Gurley would be used as a bell cow last season). In my own leagues I’ll continue drafting with the strategy I’ve always used, focusing on ADP and tailoring my draft around pricing inefficiencies rather than targeting specific positions. However, if there is an overreaction to this down-year for wide receivers, I’d be more than happy to load up on that position early, so long as that’s where the value is (according to our award-winning projections and rankings).