We are nearing the midpoint of the 2018 NFL Regular Season. It's been a wild ride so far, and we have seen some truly great and not-so-great performances. Clever fantasy football owners are looking for opportunities to buy low and sell high on potentially unsustainable performances. We spend the entire offseason predicting what will unfold once the action starts, but we can now finally react to actual data and information.

By detailing both negative and positive regression candidates, the hope is that we will uncover some of the truths behind what we've seen so far this year.

Negative Regression Candidates

Patrick Mahomes, QB, Kansas City Chiefs

Alright Pat, quit playin'.

Easily fantasy football's QB1 so far this year, Mahomes tossed four more touchdown passes in Week 8 to give him 26 on the year. That also makes 3 straight weeks with 4 scoring tosses. Over eight games played, he's averaging a crisp 26.4 fantasy points-per-game (PPG), which is almost three points better than Matt Ryan, who ranks as QB2 (23.8 PPG).

Passing touchdown regression seems certain to come -- second-place man Andrew Luck has fired 23 scoring passes, and then a slew of folks, including Jared Goff, sit at 17 scores. Where Mahomes is averaging a score once every 10.96 drop backs, Goff, for example, is averaging one per 14.88 drop backs.

Mahomes schedule is also about to get remarkably harder, including a Week 9 contest against the Cleveland Browns, who rank as the league's best passing defense per our metrics. And it doesn't stop there -- over his next five games, he will face-top 15 pass defenses in the Arizona Cardinals (14th) and Baltimore Ravens (4th).

Look for Mahomes to come back to earth a bit soon.

Deshaun Watson, QB, Houston Texans

Who didn't predict Deshaun Watson ranking as QB1 on only 20 drop backs last week? The Houston Texans fired five scores on those limited passes, which is unlikely to continue, right?

Absolutely. While last week is certainly an outlier, it's not all that unlikely in peering in at his recent passing work. Over his last three weeks, the signal-caller has only averaged 23 pass attempts.

Watson hasn't been the most efficient passer, either. Among the quarterbacks with 150 or more drop backs, he checks in 15th in numberFire's Passing Net Expected Points (NEP) per drop back (0.16). In terms of Passing Success Rate, or the rate of pass plays that generate positive NEP, he is slightly better at 19th (47.74%).

Without more efficiency or a significant rise in volume, a repeat of Week 7 seems highly doubtful.

Christian McCaffrey, RB, Carolina Panthers

Fantasy's RB10 in half-point-per-reception (0.5 PPR), is Christian McCaffrey here to stay in the top tier grouping?

It isn't looking great. McCaffrey has been a beast in the passing game, catching 44 passes for 300 receiving yards, but his rushing volume is significantly below the other league leaders. Currently, he ranks only 18th in rushing attempts (92), and he has been pretty inefficient. Among the runners with 50 or more carries (47), he clocks in 28th in Rush NEP per carry (-0.03), and ranks only 32nd in Rushing Success Rate (39.13%).

His schedule is a bit horrific, too -- in his next five games, he faces a Tampa Bay Buccaneers defense that ranks ninth against the run per our metrics, and the Seattle Seahawks, who rank 4th.

Tyler Lockett, WR, Seattle Seahawks

All Tyler Lockett is doing lately is scoring touchdowns and coming up with some pretty creative celebrations:

Currently fantasy's WR21 in 0.5 PPR formats, Lockett has built a resume on six scores in his last seven contests. But there's some red flags here, and it's primarily related to his offense.

The 'Hawks rank dead-last in the league in pass-to-run ratio (0.91), and that's put Lockett only 63rd in total targets this year (33). And their pace won't help him, either -- in games where the score is within six points, the Seahawks rank 23rd (29.83 seconds per play).

The recent performance has been fantastic, but he should be sliding out of the WR2 category in the near future.

Positive Regression Candidates

Matthew Stafford, QB, Detroit Lions

As part of a Detroit Lions offense that ranks a surprising 13th in pass-to-run ratio (1.68), fantasy's QB19 could easily be described as a disappointment. So what makes us confident in his ascent? Check out his aerial attack from Week 8 thanks to NFL.com:

Stafford started taking increasing shots downfield, recording seven pass long pass plays (over 16+ yards), connecting for a score.

While his volume is down in recent years, he was plenty busy against the Seahawks, and he has been quite efficient as a passer, ranking 10th in Passing NEP per drop (0.19).

Throw in a Minnesota Vikings pass defense that has been pretty mediocre this year, ranking 16th per our metrics, and Stafford could be on the rise fast.

Ryan Fitzpatrick, QB, Tampa Bay Buccaneers

The legend, Ryan Fitzpatrick, is back. After getting benched in a Week 4 blowout to the Chicago Bears and becoming a fantasy non-factor, he could be flying up the fantasy ranks. Peep the recent Bucs quarterback play and it becomes even more obvious:

The Tampa Bay signal-callers have performed very well, and in diving into a metric like Average Intended Air Yards (IAY), which measures the average Air Yards a passer throws on all attempts, Fitzpatrick and Jameis Winston are tied for first with a mark of 10.9 IAY.

Fitzpatrick also leads all quarterbacks with 150 or more drop backs with a Passing NEP per drop back mark of 0.52, so snatch him up as he looks to be the starter in Week 8.

Marlon Mack, RB, Indianapolis Colts

Marlon Mack may have a future in this football thing:

Still only RB27 in fantasy football, Mack has torched opposing defenses the last two weeks, racking up 258 rushing yards and three rushing touchdowns. Luckily for opposing defenses, he faces a bye this week.

While a heavy workload sometimes damages running efficiency, that hasn't been the case with Mack. He leads running backs with 50 or more carries in Rushing NEP per carry (0.31), and by a wide margin -- second-best runner Phillip Lindsay is nearly 50% less effective (0.16). He also clocks in second in Rushing Success Rate (53.03%).

Down the ranks due to a lack of volume, expect Mack to be up the boards immediately.

Keenan Allen, WR, Los Angeles Chargers

The Los Angeles Chargers rank as one of the most efficient pass offenses in the NFL. Per our metrics, they rank second in schedule-adjusted NEP per play (0.38), and Philip Rivers is firmly entrenched in the QB1 territory. So how does Keenan Allen rank 30th in 0.5 PPR formats?

It's a lack of scoring punch. Allen has only found the end zone one time this season, while he found pay-dirt six times last year. Allen's career-low touchdown reception mark, in season where he played 10 games or more, is four. The good news is that Allen is maintaining a healthy target market share in 2018, posting a mark of 25.5% (56 targets).

His upcoming Week 8 matchup could be tough against the Seahawks, but a Week 9 tilt against the Oakland Raiders, who rank second-worst per our passing metrics, should get him back on track.