There have been myriad reasons why Giants running back Saquon Barkley looks like a shell of himself since returning from a high-ankle sprain suffered Week 3 against the Tampa Bay Buccaneers.

Barkley, who amassed 2,021 total yards from scrimmage as a rookie in 2018, has not surpassed 100 rushing yards since Week 2 and is averaging under three yards per carry since his return from injury.

Wednesday, Barkley swore the is fully healthy, so blaming his injury for his steep production dip won’t fly with the reigning NFL Rookie of The Year.

However, Head coach Pat Shurmur has struggled mightily to design passing plays that get Barkley the ball in space, even though Barkley dropped a potential touchdown pass along the sideline in Sunday’s 19-14 loss to the Chicago Bears, but the second-year running back has also been unable to find his footing in the ground game.

At least part of those issues with the Giants’ ground attack fall on the shoulders of poor offensive line play, despite this being an area the Giants invested resources in rebuilding the past two seasons by drafting left guard Will Hernandez in the second-round, signing left Nate Solder to the richest contract ever awarded an offensive lineman in 2018, trading for right guard Kevin Zeitler, and adding right tackle Mike Remmers late in free agency this spring.

The offensive line as a whole has regressed from last season until now and has been a contributing factor not just in Barkley’s struggles but the barrage of pressure rookie quarterback Daniel Jones has faced in his first nine games as an NFL starter.

General manager Dave Gettleman is not without blame, because in his evaluation of Hernandez, Remmers, Solder, and center Jon Halapio, he completely whiffed on their collective ineffectiveness as run blockers, when constructing a line -- and offensive scheme -- around Barkley and the running game.

To get a sense for what the Giants’ biggest issues are along the offensive line, NJ Advance Media looked at the Pro Football Focus rankings and grades for the current offensive line, compared to the five players who started up front in the 2018 regular season finale against the Dallas Cowboys.

Here’s a look at how each individual lineman compares to last season’s group:

LT Nate Solder’s 2018 PFF ranking: No. 28

Nate Solder’s 2018 PFF grades: 74.1 overall, 75.7 pass blocking, 54 run blocking

Nate Solder’s current PFF ranking: No. 34

Nate Solder’s current PFF grades: 66.8 overall, 68.2 pass blocking, 55.4 run blocking

Solder has been a drag not just on the offensive line and a key contributing factor to the pressures that have led to Daniel Jones losing 10 fumbles -- he’s allowed 40 pressures and nine sacks in 11 games -- but also the running game. Saquon Barkley’s regression from his 2,021 yards from scrimmage rookie campaign is partially tied to what appear to be the lingering effects of his Week 3 high ankle sprain, but Solder’s poor run blocking has led to defenders making contact behind the line of scrimmage. The Giants made Solder the highest-paid offensive lineman in the NFL in 2018, but that contract looks more like an albatross with each passing week.

LG Will Hernandez’s 2018 PFF ranking: No. 38

Will Hernandez’s 2018 PFF grades: 65.8 overall, 73.1 pass blocking, 60 run blocking

Will Hernandez’s current PFF ranking: No. 38

Will Hernandez’s current PFF grades: 60 overall, 75.2 pass blocking, 45.9 run blocking

Hernandez’s ranking remains the same, but his regression as a run-blocker has been dramatic. Run-blocking was the biggest question mark facing Hernandez coming out of UTEP, and on film -- as is the case with his grades -- those concerns have been justified. Last season, Hernandez seemed to improve over the second half, but he has to this point been unable to carry that momentum from a strong finish into 2019.

C Spencer Pulley’s 2018 PFF ranking: No. 31

Spencer Pulley’s 2018 PFF grades: 55.9 overall, 70.2 run blocking, 49.4 pass blocking

Jon Halapio’s 2019 PFF ranking: No. 27

Jon Halapio’s current grades: 54 overall, 52.1 run blocking, 52.8 pass blocking

Halapio was lost for the season with a broken leg and ankle in Week 2 in 2018. Pulley seems to have been significantly stronger in run-blocking, but Halapio has the slight edge as a pass protector. If centers are the anchor of an offensive line, the Giants getting bottom third-level production from theirs the past two seasons is as fair a starting point as any when looking for reasons why this group has been a drag on the entire offense.

RG Jamon Brown’s 2018 PFF ranking: No. 91

Jamon Brown’s 2018 PFF grades: 51.7 overall, 54 pass blocking, 54.9 run blocking

RG Kevin Zeitler’s 2019 PFF ranking: No. 12

Kevin Zeitler’s current PFF grades: 70.9 overall, 73.2 pass blocking, 65.7 run blocking

Clearly, trading for Zeitler, and by extension upgrading from Brown, has been one of the few home runs in GM Dave Gettleman’s tenure. However, while Zeitler is far and away the Giants’ highest-graded offensive lineman, it is noteworthy that he fell 11 spots from being graded as the top offensive guard in the entire NFL last season. Part of Zeitler’s regression can be tied to his first season in a new blocking scheme and alongside new teammates. However, his dip in consistency begs the question whether offensive line coach Hal Hunter isn’t a significant reason the Giants have struggled along the offensive line in recent years.

Buy Giants vs. Green Bay Packers tickets: StubHub, SeatGeek

RT Chad Wheeler’s 2018 PFF ranking: No. 94

Chad Wheeler’s 2018 PFF grades: 47.4 overall, 54.7 pass blocking, 36.7 run blocking

RT Mike Remmers’ 2019 PFF ranking: No. 48

Mike Remmers’ current PFF grades: 61.2 overall, 65 pass blocking, 55.4 run blocking

There’s no question that Remmers has been an upgrade over Wheeler. However, given Remmers’ inconsistent play throughout the season, it is unlikely that he is the Giants’ long-term answer at right tackle. Remmers has surrendered 36 pressures and three sacks so far this season. If anything, Remmers was a one-season bandaid to a revolving door of dysfunction at tackle. Perhaps the Giants will invest a top pick in next April’s NFL Draft in a left tackle and move Solder to the right side.

Matt Lombardo may be reached at MLombardo@njadvancemedia.com. Follow him on Twitter @MattLombardoNFL