We've hit the double-digit mark on the NFL schedule. It's hard to believe. The horror.

After nine weeks of the 2019 NFL regular season, savvy fantasy football owners are looking for opportunities to buy low and sell high on potentially unsustainable performances. We spend the entire offseason trying to predict what will unfold once the action starts, but now we can 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

I know it felt like Patrick Mahomes of the Kansas City Chiefs was invincible, but recently, we have seen that isn't the case.

While he still ranks as one of fantasy's premier signal-callers, checking in as QB6 so far this season, expecting him to replicate the absurdity of his 2018 regular season was unlikely.

Mahomes tossed a touchdown pass on 8.6% of his drop backs last year, but that mark has seriously come back to earth (as expected) to a more reasonable mark of 5.9% this year.

There's no doubt that in terms of Passing Net Expected Points (NEP) per drop back, his mark of 0.34 has been elite. But, that too could be in jeopardy -- coming off of the bye week, Mahomes faces some ferocious pass defenses in the New England Patriots (league-best), Denver Broncos (12th), and the Chicago Bears (7th).

Obviously still a strong quarterback, it just may result in him not finishing as a top-5 quarterback.

Aaron Rodgers, QB, Green Bay Packers

Likely encouraging me just to relax, Aaron Rodgers makes his way on to the negative regression list -- and it could get ugly for the elite quarterback.

Currently sitting inside the top-10 at QB9 in 2019, Rodgers has some peculiar metrics we need to consider. His 0.24 Passing NEP per drop back ranks him seventh among quarterbacks with 100 or more drop backs, but his Passing Success Rate of 48.51% pushes him all the way down to 17th.

The schedule will not be his friend, either -- in the upcoming weeks, which are critical to consider in your fantasy football playoffs, Rodgers will take aim at the San Francisco 49ers, Chicago Bears, and Minnesota Vikings, which all clock in 11th or better via our per-play metrics.

Expect Rodgers to be a questionable play, down the stretch.

Ezekiel Elliott, RB, Dallas Cowboys

With recent difficult performances, Ezekiel Elliott is certainly not instilling a lot of confidence that running backs will continue to receive monster contracts in the near future.

While he still sits as fantasy's RB6, that rank could be back-sliding, and fast. Elliott ranks only as RB10 in Rushing NEP per carry (0.02), and he has significantly struggled in back-to-back contests with 36 combined carries for 92 rushing yards. Woof.

Oh, and there's that little problem of the New England Patriots that looms next -- they rank 10th against the run per our metrics and have allowed the fewest fantasy points to opposing running backs this season.

Darius Slayton, WR, New York Giants

It's easy to assume that players on putrid teams, like Darius Slayton, are bound to be fantasy assets because they are working in a passing game that's often trailing.

And that is true -- the New York Giants are often tasked with playing catch up.

But that doesn't mean that Slayton, who is rocketing up fantasy ranks, is here to stay. While he does have five touchdown grabs to his name this year, it comes on extremely shaky ground -- his 27 catches doesn't exactly indicate a high workload.

And since Week 8, Slayton has grabbed a touchdown pass once every 3.2 catches -- the best mark in the league. Don't go blowing the bank on a player like Slayton.

Positive Regression Candidates

Matt Ryan, QB, Atlanta Falcons

This season, as the Atlanta Falcons have floundered, has clearly not gone as planned. But, with a recent run of success lately, things are looking brighter for Matt Ryan and the team. Can it keep up?

Per our metrics, the answer is yes. He ranks 10th in terms of Passing Success Rate (51.34%), and his Passing NEP per drop back mark of 0.19 also remains solid.

He's also got a cush schedule on the horizon -- over his final six games, he faces the porous Tampa Bay Buccaneers pass defense along with the suddenly vulnerable Jacksonville Jaguars pass defense (19th).

As long as they keep up their tasty 2.09 pass-to-run ratio, Ryan makes for an intriguing option.

Leonard Fournette, RB, Jacksonville Jaguars

It's just a matter of time before Leonard Fournette finds pay dirt for his second (and third, and fourth) rushing touchdowns of the season, right?

With only one running score to his name, Fournette seems to certainly be unlucky -- he ranks ninth in carries on the year (182), and his team sports a healthy pass-to-run ratio of 1.53.

Now, Week 12 won't be a dream matchup -- the Tennessee Titans are tough against the run (third). But with upcoming matchups against the Oakland Raiders (22nd) and Los Angeles Chargers (25th), he could be gold down the stretch.

Joe Mixon, RB, Cincinnati Bengals

Winless but undeterred, running back Joe Mixon has still remained solid, despite an 0-10 start for the Cincinnati Bengals. How is this possible?

Despite those massively negative game scripts, Mixon racked up a season-high 30 carries two weeks ago in a blowout loss and last week, he still provided strong play at the position with 15 carries, 86 rushing yards and a score.

While Mixon has been working from behind, since Week 8, he ranks ninth among running backs in overall touches with a very nice 69. So the volume component is there for Mixon.

If you are looking to redeem a running back that you likely spent hefty draft equity on, don't count Mixon out just yet.

Tyler Boyd, WR, Cincinnati Bengals

I swear I am not from the Cincinnati area or even have an affinity for the city, but there's reason to believe in wide receiver Tyler Boyd bouncing back, too.

After an ugly game in Week 11, where Boyd recorded a season-low three targets paired with one catch for no receiving yards, it's important to recognize how consistently excellent Boyd has been, especially sans-A.J. Green.

Boyd has gathered seven or more targets in all but two games this year. And since the start of the 2018 season, Boyd has 692 yards after the catch -- seventh-best in the league.

His schedule is nice, too -- the New York Jets and Miami Dolphins both are in the near term, and this week's opponent, the Pittsburgh Steelers, rank in the middle for points allowed to opposing wide receivers.

Don't cast Boyd aside just yet, despite that ugly performance.