With the 2021 NFL season at its midpoint, it's becoming glaringly obvious which players haven't lived up to expectations this year.

Some of these players have suffered injuries, but they aren't busts because of that. They had been struggling before missing time and were on pace for disappointing campaigns even if they had remained healthy.

With that in mind, here's a look at eight players who were expected to accomplish big things in 2021 but have failed to live up to the hype.

RB Saquon Barkley, New York Giants

Just as New York Giants running back Saquon Barkley appeared to be rounding back into form, he suffered an ankle injury that has sidelined him for the past four weeks.

The Giants eased Barkley in at the start of the season, limiting him to 11 touches in Week 1 and 15 touches in Week 2. He then erupted for 220 yards from scrimmage and two touchdowns over the following two weeks before suffering his ankle injury in Week 5.

Barkley figures to return after the Giants' Week 10 bye, but it's fair to wonder whether he'll assume a full workload. The Giants have several offensive line starters out for the season, and their wide receiver corps has been decimated by injuries.

With their season circling the drain—they were 2-6 entering Sunday—the Giants may prioritize Barkley's long-term health. He'll be going into the final year of his contract in 2022, which means they'll soon need to make a long-term decision on the 2018 No. 2 overall pick.

It may be too late for Barkley to save the Giants' season, but he could at least put their minds at ease about his ACL with a strong second half.

WR Julio Jones, Tennessee Titans

The Tennessee Titans appeared to upgrade their passing game when they acquired Julio Jones from the Atlanta Falcons in June. However, the veteran has has struggled to find his footing with his new team.

After Jones missed seven games last year while nursing several injuries, health issues have creeped up again. The seven-time Pro Bowler suffered a hamstring injury that has caused him to miss three games. 

When he has been on the field, the 32-year-old hasn't been the same reliable playmaker that he was in Atlanta. Jones doesn't seem to have much chemistry with quarterback Ryan Tannehill, as they've connected on only 17 of 27 targets for 301 yards.

Jones found pay dirt 60 times with the Falcons, but has zero touchdowns since joining the Titans.

With superstar running back Derrick Henry out indefinitely with a foot injury, the Titans need more out of Jones. If he can't perform at a high level, they might struggle over the second half of the campaign.

QB Patrick Mahomes, Kansas City Chiefs

Kansas City Chiefs quarterback Patrick Mahomes started the 2021 season off hot, averaging more than 300 passing yards while throwing at least three touchdowns in each of his first four games. However, he's been far more inconsistent in recent weeks.

The Chiefs' closer-than-expected 13-7 win over the Aaron Rodgers-less Green Bay Packers on Sunday was Mahomes' first interception-free game since Week 1. However, he finished with a season-low 166 passing yards and only one touchdown.

Mahomes had never averaged fewer than eight yards per passing attempt prior to this season, but he's at 7.0 this year. He has a career-low QBR of 54.3, and nine games into the season, he's already two interceptions away from tying his career high (12).

In an interview with ESPN's Lisa Salters last week, Mahomes reflected on the Chiefs' up-and-down start to the season.

"We expected to be in the playoffs," he told Salters (h/t Jacob Camenker of Sporting News). "We expected to have another chance at going to the Super Bowl. But it takes the daily process of every single day to make it there, and we're noticing that now, that we've got to go back to the drawing board and put in that work."

While Mahomes has been far from the worst quarterback in the league over the first half of the season, he's failing to live up to the high bar that he set over his incredible first three years.

RB Clyde Edwards-Helaire, Kansas City Chiefs

Like Saquon Barkley, Kansas City Chiefs running back Clyde Edwards-Helaire started the year tepidly. He rushed for only 89 yards on 27 carries over the first two games, and he added only three receptions for 29 yards.

He seemed to start gaining some momentum in Weeks 3-4, racking up 202 yards on 31 totes and adding four receptions for 21 yards and a pair of scores, but he couldn't build one the best stretches of his career.

The 22-year-old had a brutal half in Week 5's AFC Championship Game rematch with the Buffalo Bills, rushing for a mere 13 yards on seven carries, before going down with a knee injury that has kept him sidelined since.

With Darrel Williams finding the end zone at a more reliable rate—the backup had two rushing touchdowns before CEH's injury and scored twice in his Week 6 start—the Chiefs may choose to split time between the backs more evenly when Edwards-Helaire returns.

Derrick Gore also emerged last week, picking up a respectable 48 yards and a touchdown on 11 carries. The 26-year-old could earn more playing time based on that performance, which makes Kansas City's backfield one of the more unpredictable platoons going forward. 

WR Robert Woods, Los Angeles Rams

The Los Angeles Rams' passing offense has taken off since the acquisition of quarterback Matthew Stafford, but wideout Robert Woods hasn't benefited much from the change under center.

Woods has only 38 receptions on 59 targets for 458 yards and four touchdowns this year. That puts him on a similar pace to last year's 90 receptions on 129 targets for 936 yards and six scores. 

With Jared Goff no longer under center and L.A. ranking fourth leaguewide in passing offense, Woods should theoretically be producing at a much higher level. Instead, he has only 66 more yards and one more score than Van Jefferson, who has played 81 fewer snaps.

Teammate Cooper Kupp has been the primary beneficiary of Stafford's arrival. Kupp has a league-leading 924 receiving yards and 10 touchdowns on 63 catches.

Woods had a 12-catch, 150-yard outing in Week 5, but he has failed to haul in more than six catches or 70 receiving yards in any of his other games. The Rams will need likely more out of him to win the Super Bowl.

RB Miles Sanders, Philadelphia Eagles

The Philadelphia Eagles have one of the league's most promising young players in running back Miles Sanders, but they've underutilized him. 

Sanders has 300 rushing yards on only 63 carries and 19 catches on 24 targets for 118 yards, although he has yet to score a touchdown this season. Based on his average of 4.8 yards per carry, he could conceivably put up around 1,600 yards on the ground if he had 20 carries per contest over a 17-game season.

Instead, the Eagles coaching staff has gone long stretches without calling Sanders' number. The 24-year-old had fewer than 10 carries in four of his seven starts, including a mind-boggling two rushes in Week 3.

Sanders will now have to wait for his chance to assume a larger role in the offense. He was carted off the field in Week 7 with an ankle injury and was subsequently placed on injured reserve.

Sanders might see even fewer carries when he comes back. With rookie Kenny Gainwell getting more experience and Boston Scott and Jordan Howard each punching in a pair of touchdowns in Week 8, the Philadelphia backfield looks more crowded than ever.

Sanders is still the most talented back of the bunch, but he may not get a chance to put his gifts on display if he continues touching the ball fewer than 12 times per game.

LB Jaylon Smith, Free Agent

Jaylon Smith signed a five-year, $64 million contract extension with the Dallas Cowboys and made the Pro Bowl in 2019. Two years later, he's been cut by two teams within a month.

Smith once rated among the NFL's best linebackers early in his career. Pro Football Focus gave him a star-like 84.0 grade in 2018, and he earned a respectable 70.2 grade during his Pro Bowl campaign in 2019.

However, Smith fell off hard last season, finishing with a disappointing 54.2 PFF grade. The Cowboys added insurance at the position this offseason, signing Keanu Neal in free agency and selecting Penn State linebacker Micah Parsons in the first round.

Smith started only two games for the Cowboys this year before they released him in early October. The injury-plagued Green Bay Packers signed him shortly thereafter, but he played only 27 non-impactful snaps across two games before they released him as well.

It remains to be seen if another team will take a chance on the 26-year-old. But after flaming out with two separate NFC contenders in the span of a month, Smith's prospects look bleak.

WR Allen Robinson II, Chicago Bears

Chicago Bears wideout Allen Robinson hauled in a career-high 102 passes for 1,250 yards and six touchdowns last year, but he's off to a miserable start this season. He has only 26 catches for 271 yards and one touchdown heading into Monday Night Football.

Robinson has started every game this season and has played 85 percent of the Bears' offensive snaps. He's also drawn 44 targets, second only to Darnell Mooney among all Bears pass-catchers.

Robinson appears to lack chemistry with rookie quarterback Justin Fields. Mooney has become Chicago's most dangerous receiving weapon this season, putting up 409 yards and a score on 33 receptions.

The Bears used the franchise tag on Robinson this offseason, and they opted against shipping him out ahead of Tuesday's trade deadline. He needs to find a way to get in sync with Fields moving forward.

If Robinson can't help out Chicago's slumping passing attack, this team will find it tough to contend in the back half of the season.

All stats via Pro Football Reference and are accurate heading into Week 9.