As you get ready for fantasy football 2021, be sure to get plenty of practice by using our Mock Draft Lobby.
Football statistics can prove hard to predict, but history continues to show that projecting touchdown regression to the mean is significantly easier than you might imagine.
The 2016, 2017, 2018, 2019 and 2020 versions of this article provide overwhelming evidence.
Note that this study is limited to regular-season rushing and receiving data.
There are 64 names here and, in 59 cases, the player scored fewer touchdowns the following season. That's an absurd hit rate of 92% and all five exceptions came during the historically offensive 2018 and 2020 seasons (not to mention that four of Taysom Hill's nine scores came during his four unexpected starts at QB). Even if we cross off players who barely saw the field (David Johnson, Karlos Williams, Antonio Brown, Christian McCaffrey), the evidence remains extremely strong.
This is far from surprising, as we've learned over the years that players simply cannot sustain extremely high scoring rates. It's not a knock on their talent. Scoring is simply more about opportunity.
You want proof? Good, I have it.
During the 2009 to 2019 seasons, there were 207 instances in which a player totaled 10 or more touchdowns as a rusher or receiver. Of those players, a whopping 177 (85.5%) scored fewer touchdowns the next season and the average change was a decrease of 5.3 TDs. Of the 45 instances in which a player scored 14-plus touchdowns, 43 scored fewer times the next season (average dip of 8.2 TDs). The only exceptions were Todd Gurley II (19 in 2017, 21 in 2018) and Marshawn Lynch (14 in 2013, 17 in 2014).
Last season, Alvin Kamara (21), Davante Adams (18), Tyreek Hill (17), Derrick Henry (17), Dalvin Cook (17) and Adam Thielen (14) were the six players who reached 14 offensive TDs.
As if that's not enough to help us predict touchdown regression, we also have opportunity-adjusted touchdowns (OTD). In this piece, I'll be referencing OTD, which is a statistic that weighs every carry/target and converts the data into one number that indicates a player's scoring opportunity. Put another way, it is how many touchdowns a league-average player would've scored with the exact same opportunity as the player shown.
A careful examination of each of the below player's 2020 usage tells us that we should expect a drop in scoring production this season.
Be sure to also check out the list of players who will score more touchdowns this season. Note that this study is limited to regular-season rushing and receiving data.

Robert Tonyan, TE, Green Bay Packers | 2020 TDs: 11 | 2021 projected TDs: 6
Tonyan is 2021's poster boy for statistical regression to the mean. His 18.6% TD rate in 2020 was easily highest in the NFL and the next-closest player with 50-plus targets was Adam Thielen at 13.1%. Consider this: From 2009-19, 29 tight ends posted a season with a TD rate at or above 8.5% on 50-plus targets and then saw 50-targets again the next season. Of those 29 TEs, 27 had a lower TD rate and 27 scored fewer TDs the next season. Tonyan's 59 targets ranked 22nd at the position in 2020 and he'll need a big boost in that department this season in order to offset inevitable regression and repeat as a top-five fantasy tight end.

Alvin Kamara, RB, New Orleans Saints | 2020 TDs: 21 | 2021 projected TDs: 11
Kamara's 21 offensive TDs last season paced the NFL and tied for 15th most in a single season in league history. The gap between his actual TD total and expected total (12.3) was the largest in the NFL. Kamara ranked fifth among backs in touches (270) and eighth in carries inside the 5-yard line (12), so he was obviously way over his head. Kamara has 13 or more scores in three of his four NFL seasons, though he was limited to six on 253 touches in 2019. In addition to the inevitable TD regression to the mean, Kamara's scoring will also be affected by Drew Brees' retirement.

Adam Thielen, WR, Minnesota Vikings | 2020 TDs: 14 | 2021 projected TDs: 9
Thielen has paced the WR position in TD rate each of the past two seasons, but his 13.1% rate in 2020 was more than double his previous career rate and his 14 scores were more than half his previous career total (25). His 20 end zone targets were three more than any other player and his 13 TDs on those plays are the most the league has seen since Rob Gronkowski converted 13 in 2011. The 31-year-old will remain a featured target near the goal line, but his scoring pace will surely slow down.

Tyreek Hill, WR, Kansas City Chiefs | 2020 TDs: 17 | 2021 projected TDs: 11
Hill's elite playmaking ability and terrific connection with Patrick Mahomes has allowed him to "break" TD regression to the mean throughout his career (47 TDs, 28.2 expected TDs), but even he is a long shot to keep up his torrid 2020 pace. Hill caught a career-high 15 TDs (he averaged 8.0 in his first four seasons) and ran for two more on 13 carries (he totaled four rush TDs in his first four seasons). A return to earth is on the horizon.

Davante Adams, WR, Green Bay Packers | 2020 TDs: 18 | 2021 projected TDs: 12
Adams has caught 58 TDs since 2016, which is 11 more than any other player. Of course, during that span he cleared 13 TDs in a season only once and that was the 18 he scored in 2020. Adams is fantasy's top WR and a good bet for double-digit TDs (he's achieved that in four of the past five seasons), but odds are 2020 will go down as his career high in the TD department.

Chase Claypool, WR, Pittsburgh Steelers | 2020 TDs: 11 | 2021 projected TDs: 7
Claypool was a top-25 fantasy WR as a rookie, but the Notre Dame product benefited greatly from hitting on low-percentage plays. Claypool ranked 47th at WR in routes (429) and was outside the top 25 in targets (107), receptions (62), yards (873) and end zone targets (seven), but still managed to catch nine TDs while adding two more on 10 carries. Even if Claypool's usage increases in his second season, his TD total is likely to drop.

Jonnu Smith, TE, New England Patriots | 2020 TDs: 9 | 2021 projected TDs: 4
Smith signed a sizable contract with New England during the offseason after never finishing higher than 15th at TE in routes, targets, receptions, yardage or fantasy points during four seasons in Tennessee. He had also failed to clear three TDs in a season prior to exploding for nine in 2020. Smith was targeted "only" 65 times (17th most at TE) and his 12.3% TD rate was third highest in the NFL. Expect the short-area target to crash back to earth in the TD department in his first season with the Patriots.

Derrick Henry, RB, Tennessee Titans | 2020 TDs: 17 | 2021 projected TDs: 14
I don't like being in the business of doubting Henry, but he scored 17 TDs last season after scoring 18 in 2019. That may seem like a good thing, but consider that LaDainian Tomlinson is the only player in NFL history with 17-plus TDs in three consecutive seasons. The good news is that Henry has led the league in carries and rushing yards each of the past two seasons and his career-high 17 carries inside the 5 ranked fifth in 2020. Bet on a slight step back in 2021.

JuJu Smith-Schuster, WR, Pittsburgh Steelers | 2020 TDs: 9 | 2021 projected TDs: 6
Smith-Schuster had never cleared seven offensive TDs in a season prior to making the leap to nine last season. His usage suggests the output was fluky, as he had a decent number of end zone targets (11), but not much additional work near the goal line (5.8 OTD).
Smith-Schuster entered 2020 having scored 17 offensive TDs with a 16.4 OTD, so he had been pretty much right on track prior to what appears to be a fluky showing last season. He is on the field a ton (first at WR in routes in both 2018 and 2020), but we should expect his TD total to dip this season.

Ryan Tannehill, QB, Tennessee Titans | 2020 TDs: 7 | 2021 projected TDs: 4
Tannehill's passing efficiency has been so ridiculously good that we could probably feature that here, too, but for now we're just focused on his rushing. Tannehill scored six TDs (7.9 OTD) on 248 carries during his first six NFL seasons, but has racked up 11 TDs (4.9 OTD) on 86 carries during a pair of seasons in Tennessee. He carried the ball inside the 5 only three times last season, but managed seven TDs (3.2 OTD) on 43 attempts. A return to earth is likely in 2021.

A.J. Brown, WR, Tennessee Titans | 2020 TDs: 11 | 2021 projected TDs: 9
Tannehill's top target has been nothing short of elite in the scoring department so far in his young career. The 2019 second-round pick has caught 19 TDs on 190 targets and also has a rushing score on one of his three carries. Brown ranked fifth in the NFL with a 9.5% TD rate as a rookie and actually increased that to 10.4% (seventh highest) in 2020. Brown has done all this despite an 8.4 OTD during the two seasons. In fact, that 6.5 gap between his 11 TDs (12th most) and 4.5 OTD (106th) last season was fourth highest in the entire NFL. Brown has a high ceiling, but we should still bet the under based on his usage.
Others: Jamison Crowder, WR, New York Jets; Mike Evans, WR, Tampa Bay Buccaneers; James Robinson, RB, Jacksonville Jaguars; Kyler Murray, QB, Arizona Cardinals; Dalvin Cook, RB, Minnesota Vikings.