The running back position is arguably fantasy football's most volatile. Preseason expectations often go flying out the window once the season begins, and every year sees plenty of surprises, both good and bad. That never stops us from trying to make sense of what happened, with an eye toward making better prognostications next time around.

In order to peer into the future, we must first understand where we came from. Here then, are the biggest running back risers and fallers of 2016.

A quick note about methodology: I used 12-team PPR preseason ADP from Fantasy Football Calculator, and compared it to postseason positional finish. Rather than focus on the greatest raw change in rank, I focused on players that played the entire season, and were drafted outside of, but finished within the top tier of RBs.

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2016's Running Back Risers

Jay Ajayi, Miami Dolphins

Preseason ADP Rank: 44
Positional Finish: 11

There was a lot to like about Ajayi when he came out of college. However, after spending his rookie season well behind Lamar Miller on the depth chart, and with injury concerns lingering, expectations were low heading into 2016. When he began the season as a healthy scratch, and played behind Kenyan Drake in Week 2, even his RB44 ADP looked overly optimistic. Finally, in Week 5, he broke through with a TD. From there he exploded, posting three weeks with over 200 yards rushing, and another with over 100. He scored double-digit PPR points in eight of 11 games to close the fantasy season. Looking ahead, the Dolphins continue to voice enthusiasm about his development and speak of him as their lead back of the future. The main concern is a relative lack of involvement in the pass game. If he can find a way to catch a few more balls, he could repeat as a top-12 RB in 2017.

LeGarrette Blount, New England Patriots

Preseason ADP Rank: 38
Positional Finish: 9

Judging by his ADP, nobody expected a career year from the Patriots pounder. Could we have seen this coming? In hindsight, drafters probably didn't pay enough attention to Dion Lewis' injury situation. In fairness though, the New England backfield has historically been difficult to project. Blount turned a very healthy 62 percent of team attempts into 1,161 yards and 18 TDs. So we might have expected a bigger role, but I don't think anyone could realistically have foretold that many scores. Hopefully, you were one of the lucky ones to enjoy Blount's magical 2016. As for 2017, Blount is a 30-year-old free agent, so it's hard to project his role, let alone his team. No matter what, he's almost certain to come in well below 18 TD. I still expect him to have value, but to perform much closer to his career norm of about eight PPR points per game.

Frank Gore, Indianapolis Colts

Preseason ADP Rank: 29
Positional Finish: 12

The fantasy football dictionary defines "consistency" as "Frank Gore." He's gone over 1,000 yards rushing in nine of 12 seasons. His three misses came as a rookie in 2005, in an injury-shortened 2010, and by just 33 yards in 2015. Sure, he was well into his 30s, but his role on offense was locked in, and his pedigree suggested he'd still be productive. In 2016, he added 38 catches, a number very similar to the 34 he posted in 2015, which was a solid boon to his PPR scoring. What about next year? We'll have to keep an eye on the draft and free agency, but if he keeps his role, expect similar results. The Colts offense is good enough to provide ample opportunity, and Gore's TD numbers in 2016 were in line with his career rates, so he's not nearly the candidate for regression that Blount is.

Melvin Gordon, San Diego Chargers

Preseason ADP Rank: 21
Positional Finish: 7

Speaking of regression. Gordon scored zero TD as a rookie on 184 attempts. That's historically rare. That lack of rookie production contributed to a low ADP, but Gordon rewarded those who took him. Some positive regression in scoring combined with Danny Woodhead's injury led to a premiere workload. Gordon finished in the top 10 in rushing attempts, and the top 15 in RB pass targets. His RB7 finish came in just 13 games; on a per-game basis he finished as the RB5. Expect more of the same going forward. Woodhead is a free agent who may or may not return. Gordon demonstrated the ability to handled a heavy workload in both facets of the game, and also plays in an offense that should be even better next year.

2016's Running Back Fallers

Lamar Miller, Houston Texans

Preseason ADP Rank: 4
Positional Finish: 19

Things looked so good heading into 2016. A big free agent contract and a new team suggested a heavy workload on a team that tended to play fast and run more than expected. Then Brock Osweiler happened. Houston still finished near the top of the league in total plays, but only managed to score on 31.2 percent of their drives, near the bottom of the league. Miller's workload was there - 268 carries - but the scoring wasn't. He finished with just six total TD. In a vacuum, an RB19 finish isn't awful. But it is when he was a top-four selection. Three of the four RB drafted around him (David Johnson, Ezekiel Elliott, and Le'Veon Bell) handily crushed his production, leaving drafters of Miller with a big deficit to make up. Miller could end up being a player to target heading into 2017. He should be able to get a similarly large workload, and there's a good chance that his scoring rebounds.

Todd Gurley, Los Angeles Rams

Preseason ADP Rank: 2
Positional Finish: 15

Gurley was the other major disappointment among the early-drafted RBs. Like Miller, his overall finish wasn't terrible, but the margin by which he under performed his ADP likely hurt his fantasy owners significantly. That's especially true when you consider that Gurley was just the RB25 in per-game scoring. With just two performances over 19 PPR points, he seldom helped his owners win. Like Miller though, there's a lot to like heading into 2017. He's still young, and although the Rams offense probably won't be great, it probably will be a lot better under new head coach Sean McVay. Efficiency measures aren't very sticky from one year to the next, meaning there's a really good chance he improves on last year's 3.2 yards per carry. If he keeps a similar workload, which seems very likely, he could easily be a top-10 RB.