One of the most interesting statistics from last year that I've been trying to wrap my brain around is the massive increase in rushing touchdowns and the decline of receiving touchdowns.

Just five of last year's top-12 fantasy football wide receivers (PPR format) finished the season with double-digit scores. More specifically, just five of last year's entire wide receiver group scored 10 or more touchdowns. It's the lowest output we've seen over the past five years.

Over the past several years, the NFL has undoubtedly turned into a more pass-heavy league. Pass attempts have steadily been on the rise while rushing attempts have steadily declined.

The 2016 season was no different. Despite "the return of the running back" from a fantasy production standpoint, pass attempts stayed right around the same as 2015 (an all-time high), while the average team's rushing attempts fell for the fifth consecutive season.

Top running backs, though, saw their touchdown totals rise dramatically.

Given the league's steady decline of rushing attempts, are these running backs becoming more efficient with their touches and scoring more frequently?

They certainly did last year with us seeing the largest amount of rushing touchdowns among the top-12 PPR backs dating back to 2009 (125).

But why?

Peeling Back the Curtain

It wasn't just the top-12 running backs that were scoring. Last season saw the most rushing touchdowns since 2008 (478) -- an era when teams ran the ball 44.6 percent of the time compared to 2016's 40.7 percent.

So if we're seeing a massive decrease in rushing attempts, how did we find so much scoring from rushing last year?

Well, 2016 saw an abnormally high number of rushing touchdowns from inside the opponent's 1-yard line. It was actually the highest number of rushing touchdowns we've seen since 2008 (154).

Why was that? There wasn't a significant increase in touchdown rate. What could have led to so many scores for these running backs to capitalize on?

A big reason could be due to penalties.

Defensive pass interference (DPI) calls were at an all-time high in 2016. There was an average of 9.03 DPI penalties per team league-wide, a number that was well north of recent years. There has also been an increase in the number of defensive holding calls over the past three years, leaving 2016 as one of the most penalized seasons we've ever witnessed.

Whether through DPI or holding, there were an astronomical number of plays that set up 1st-and-goal from the 1-yard line in 2016. To be exact, there were 74 occurrences of either DPI or holding that set up an offense at the 1-yard line in 2016. That is almost double the amount we saw in 2015 (43).

Some of these defensive infractions happened on the same particular series, leaving 68 total opportunities for offenses to score a touchdown.

And that's exactly what offenses did, scoring a touchdown on 63 of the 68 opportunities -- 92.6 percent of the time, offenses were able to finish the drive with a touchdown. Four of the remaining five opportunities ended in field goals, raising the total scoring percentage to 98.5 percent. The only unsuccessful attempt following a penalty-induced, 1st-and-goal from the 1-yard line was a strip-sack by Jaguars' rookie Yannick Ngakoue on Philip Rivers, which forced a turnover.

Given the high probability for a team to convert from just a yard out, those touchdown opportunities from the 1-yard line provided a massive swing to scoring for running backs, often at a wide receiver's expense. A solid 48 of the 63 penalty-leading touchdowns (76.2 percent) came via the ground. When given the chance to score, running backs took advantage and converted often for six points.

So, okay, that's (somewhat) interesting data. But how can we utilize it to our advantage moving forward?

Players With Positive Regression on their Side

Touchdowns can be fluky. It's difficult to project year over year touchdown rates, and it's often one of the least predictive statistics we can utilize. However, it's still important to chase these targets and opportunities, particularly with a four- or six-point fantasy bonuses within a player's grasp.

The following quarterbacks drew multiple defensive pass interference calls in the end zone for their team and just missed out on scoring touchdowns:

After adding a four-point touchdown bonus and the respective yardage for these missed opportunities, quite a few quarterbacks moved up the fantasy rankings.

The unfortunate leader in missed passing touchdowns opportunities last year was quarterback Derek Carr, who had a whopping nine opportunities to score fall through his fingers. Two of these drives had multiple infractions and he was able to convert one of the penalties into a 1-yard pass to Andre Holmes, so Carr actually had a chance for an additional six passing touchdowns had things broke his way. Finishing as the overall QB10 with 28 touchdowns, Carr could have netted a QB6 finish had his receivers converted those opportunities for scores. The arrow is pointed way up for Carr who finished the year eighth in Passing Net Expected Points (NEP).

Philip Rivers missed out on four scoring opportunities last year due to defensive penalties. Melvin Gordon was the lucky recipient taking most of those 1st-and-goal opportunities across the pylons for six. Rivers has the potential to far exceed his current QB15 average draft position.

The New England Patriots quarterbacks combined for a total of six missed scoring opportunities, Tom Brady with four and Jacoby Brissett with two. After averaging 21.5 fantasy points per game (third-best) and 0.35 Passing NEP per drop back (second-best), it's scary to think what Brady could be capable of in 2017 given the offensive additions the Patriots have made.

Andy Dalton just missed out on scoring an additional three passing touchdowns last year. Perhaps with another year working in offensive coordinator Ken Zampese's system, the two of them can find more effective ways allowing Dalton to capitalize drives with passing touchdowns.

While there were minor shakeups at the quarterback position, there could've been some much larger implications at the receiver position due to the scoring of the position (six-point touchdowns, 0.10 points per yard gained). These players drew multiple defensive pass interference or holding calls in the end zone last year:

The wide receiver with the most missed touchdown opportunities because of defensive penalties was Amari Cooper. Cooper had four different chances to score but ended up being a big target for defensive backs to interfere with in the end zone. Cooper has been criticized for his work in the red zone (by myself included), but I believe we'd be looking at Cooper in a much different light had he been able to capitalize on those penalty-induced chances. We'd be looking at a 22-year old wide reciever coming off an 87-catch, 1,197-yard, 9-touchdown sophomore campaign. If there's one player likely to see a boon in positive touchdown regression in 2017, my money is on Cooper.

The wideout that tied Cooper for the most missed scoring opportunities was Cincinnati's Brandon LaFell. LaFell just missed out on an additional four scoring opportunities, finishing the season as the overall WR35 in PPR scoring last year. If he'd been able to capitalize on those scoring chances, he would've finished as the WR18. That upside has me chasing him in every draft.

There were minor fantasy increases for the other multiple missed touchdown players, but it's interesting to note Odell Beckham would've climbed to the top wide receiver spot.

While looking at these numbers and missed opportunities, it's important to keep in mind that while they were unsuccessful, the play-calling allowed for a chance for these players to score. Targets are the lifeblood of fantasy production (LeGarrette Blount had the most touchdowns from the 1-yard line stemming from penalties among all players with five. Latavius Murray was second on this list with four. Blount remains unsigned, and Murray moves to Minnesota behind one of the worst run-blocking units in the league. It wouldn't be shocking to see both decline in touchdowns in 2017.

Lamar Miller and Melvin Gordon each scored three times from the opponent's 1-yard line because of defensive passing penalties. Miller scored just five total rushing touchdowns last season, and considering three of them came via these penalty circumstances, he's a player I'm currently fading at current cost.

Gordon, on the other hand, had very little competition for touches last year in San Diego, garnering 71.5 percent of the running back touches in the 12 full games he played last year. It wouldn't be that surprising to see San Diego added someone to the backfield in this year's draft to help keep Gordon fresh after he was on a 335-touch pace last year.

An interesting note from the defensive side of the ball -- there were a good number of repeat offenders, but nobody had more infractions called against them than Jonathan Cyprien (3). All three of his end zone infractions led to 1-yard rushing touchdowns for the opposing offenses.

Conclusions

We saw a massive increase in rushing touchdowns, opportunities from the 1-yard line, and rushing touchdowns from the 1-yard line in 2016, despite a continuing league-wide trend in decreasing rush attempts. The meteoric rise in end zone penalties last season helped support rushing touchdowns from the 1-yard line to the highest rate we've seen since 2008.

This big jump seems like a significant outlier given the league's heavy pass emphasis we see today.

The NFL is still a heavy pass-first league, and the moniker of 2016 being the "return of the running back" seems a bit aloof to the point. We saw a rare circumstance last year with wide receivers reaching the low-end of their range of outcomes. That's just variance. Wide receivers should see a rebound in touchdown scoring in 2017, and we should have that mindset in fantasy football drafts.