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

Andrew Luck, QB, Indianapolis Colts

There's no doubt that Andrew Luck appears to be rounding into form after missing some serious time with shoulder ailments. This year's QB5 so far in fantasy football, Luck has built a solid resume based upon the Indianapolis Colts' healthy pass-to-run ratio (2.00), which ranks as fourth-best in the league. He's also facing an Oakland Raiders pass defense this week that ranks second-worst, per our metrics, and the Colts work quickly -- in terms of situation-neutral pace, the Colts are the fastest team in the league (26.91).

But a deeper dive among our advanced metrics shows that Luck hasn't been all that solid. Among the 29 passers with at least 150 drop backs, Luck clocks in only 21st this season in numberFire's Passing Net Expected Points (NEP) per drop back (0.08). In terms of Passing Success Rate, or the rate of pass plays that generate positive NEP, Luck is slightly better at 18th (47.98%).

While the signal-caller certainly has the benefit of a heavy passing attack, his true efficiency may cause him to slide out of the top-five fantasy QBs very soon.

Alvin Kamara, RB, New Orleans Saints

Guys, it's time to be worried about Alvin Kamara.

While we knew that Kamara was going to lose some time to Mark Ingram upon his return, it's been fairly drastic so far. After functioning as a bell cow back in the early weeks (85% snap rate in Week 3), Kamara is now in a time share, recording 70 offensive snaps to Ingram's 71 in Weeks 5 and 7. Peeping their touches in Week 7, Kamara held the slight edge over Ingram by a mark of 19 to 14.

This doesn't mean that Kamara cannot be a very valuable fantasy back, but if this plays out as a true time-share, it may be hard for Kamara to maintain his lofty status.

Tyreek Hill, WR, Kansas City Chiefs

The cheetah, Tyreek Hill, is certainly no stranger to the big play:

Fantasy's WR2 so far this year in half-point-per-reception (0.5 PPR) formats has been a major part of the Kansas City Chiefs 6-1 start. But can he stay among the wide receiving elite?

While he leads the league in receiving touchdowns, he ranks only 13th so far in targets. He's also scored four times in the last two games, and his touchdown rate per target and reception outpaces the leaders and his own 2017 marks:

Hill is still an elite fantasy wide receiver asset, but even compared to his lofty standards in the past, the rate at which he's scoring touchdowns is likely to fall off.

Michael Roberts, TE, Detroit Lions

So who is this Michael Roberts tight end that exploded in Week 7 for two touchdowns on three catches, and do we want to own him in fantasy?

Returning from an injury, and part of a Detroit Lions offense that has been one of the pass-heaviest attacks in the league, owning pass catchers on this team is certainly not a bad option. And at a position that's usually hard to roster, while Roberts his a bit of an unknown commodity, those two scores left him tied for second as fantasy's TE2.

There's a few warning signs, a few obvious and others not so much. Certainly, this scoring pace won't keep up, and it's interesting to note that the emergence of Kerryon Johnson has dropped the Lions to 15th in pass-to-run ratio (1.54). Roberts snap rate was also a bit frightening, as he ranked last among the team's tight ends in terms of offensive snap rate, recording a mark of 30% to Luke Willson's 64% and Levine Toilolo's 33% mark.

He's certainly not a costly investment, but he may not return Week 7 performances again this season, either.

Positive Regression Candidates

Brock Osweiler, QB, Miami Dolphins

I'm not sure that anyone saw this coming for Brock Osweiler:

Bouncing his way around, and 2017's QB35, finally landed as a member of the Miami Dolphins, Osweiler has been sneaky good in his first two starts in South Beach.

Osweiler checks in with a cool 0.37 Passing NEP per drop back mark, and he's also taking plenty of shots deep(via NFL Next Gen Stats):

Osweiler attempted eight deep throws (travelling 16-plus yards downfield), which tied him for seventh in Week 7 action.

Given his efficiency, his willingness to take shots deep, and facing a porous Houston Texans pass defense that ranks fifth-worst per our metrics, Osweiler is worth some attention.

Jameis Winston, QB, Tampa Bay Buccaneers

With three turnovers in Week 7, leading to a QB16 finish, where do we see Jameis Winston heading for 2018?

It seems like his arrow is pointing up. Picking up right where Ryan Fitzpatrick left off, Winston leads the league in Average Intended Air Yards (IAY), which measures the average Air Yards a passer throws on all attempts, among current NFL starters, with a 10.2-yard average.

Despite a mediocre Passing NEP per drop back mark (0.11), Winston flies up the rankings in terms of Passer Success Rate (55.23%, third). With a date on tap against a Cincinnati Bengals defense that's allowed the fifth-most points to opposing quarterbacks (22.5), Winston makes for a juicy play in Week 8 and beyond.

Odell Beckham, WR, New York Giants

In the midst of a massive fire sale for the New York Giants, how should we handle Odell Beckham?

Currently only fantasy's WR9 in 0.5-PPR formats, his two touchdown receptions, as mentioned above, seem to be a bit low.

When looking a bit closer, there's plenty of volume working to Beckham's favor. He currently sits fourth in the NFL in targets (80), and he is one of three wide receivers with a Target Air Yards Share of over 40% (43.88%).

While this certainly has been a rough 2018, look for Beckham to start moving up the wide receiver rankings.

Juju Smith-Schuster, WR, Pittsburgh Steelers

JuJu Smith-Schuster has slid out of the top-10 fantasy wide receivers this year, and quiet Weeks 4 and 5 can be blamed, where the pass catcher totaled only 94 receiving yards. Coming off a bye, were those weeks an aberration or a warning sign of things to come?

The good news is those seem like blips on the radar screen. Juju plays in an offense that ranks fourth in pass-to-run ratio (2.06), meaning the volume will certainly be there, and despite the presence of All-World receiver Antonio Brown, Smith-Schuster has managed a robust 24.1% target market share.

This week, the Steelers will try to avenge an opening-week home time to the Browns, who've allowed the seventh-most receiving yards per game. Don't expect the second-year man out of USC to stay out of the top-10 for long.