The Biggest Red Flags in the 2018 NFL Free-Agent Class

Every year, there are at least a handful of players available during the NFL free-agency period who would be riskier signings than others. These red-flag types are often disgruntled veterans or immense but injury-prone talents who give teams pause when it comes to dishing out long-term deals with significant dollars attached. 

Sometimes, these red-flag players turn things around with their new franchises, finally getting healthy or improving their attitudes in their new digs. That's was the case last season with Alshon Jeffery, who bet on himself with a one-year deal and wound up serving as a key player for the Philadelphia Eagles during their Super Bowl run.

There have also plenty of other instances when organizations have been burned after doling out a new contract, with the cautionary tale of Albert Haynesworth signing a $100 million contract with the Washington Redskins and basically giving up on football upon cashing the check serving as a perfect example of this.

There are a number of players who fit the red-flag bill set to hit the open market this offseason. While they have all had their moments during their time in the league, suitors should be wary of committing too much toward signing the players highlighted in this article and exercise caution when structuring their new contracts.

Read on for a look at the biggest buyer-beware players in the 2018 NFL free-agency class.

It's difficult to fathom, but Sam Bradford is one of the higher-paid quarterbacks in league history. Three teams have sunk a combined nine figures into the former No. 1 overall pick and the results have been rather underwhelming. At 30 and with a long history of injury, there's no longer much upside with Bradford, but that won't stop an organization desperate for production under center from shelling out big money for his services this offseason.

Bradford participated in one full game during the 2017 season, opening the year by completing 85 percent of his passes for 346 yards and three touchdowns against the New Orleans Saints. He missed a month after that contest with a non-contact knee injury before giving it another go in October against the Chicago Bears.

He wasn't able to finish the game after that same knee suffered enough swelling and soreness before halftime to push backup Case Keenum back into action for the remainder of the campaign. Bradford had his knee cleaned up in November—the third surgery on it in total—and was reactivated in January for the playoffs in a reserve role, but without any meaningful snaps, it remains to be seen how healthy he is.

Vikings head coach Mike Zimmer described the knee as "degenerative" when speaking to the media at the scouting combine, a concerning sign for whichever team inks the quarterback to a new contract. However, Zimmer also mentioned Bradford was out skiing—not the most practical activity for someone with a bum knee—and there are rumors Minnesota is considering bringing him back into the fold if it loses out in the Kirk Cousins sweepstakes, which means the team would prefer to move forward with him rather than Keenum or Teddy Bridgewater.

That's a lot of risk for a team that just made a deep foray into the postseason with a backup under center, especially since Bradford hasn't played 16 games since 2012, notably missing all of the 2014 campaign, more than half of the 2013 season and most of last year. The Vikings would be gambling they wouldn't need to rely on a second-stringer to try to guide the franchise back to the NFC Championship Game and beyond.

Any club willing to pay Bradford market price—which could be at least $12 million annually—will keep its fingers crossed the signal-caller can produce the way he did in 2016, when he completed a then-NFL record 71.6 percent of his passes for 3,877 yards and 20 touchdowns against five interceptions during his first season in the Twin Cities.

He can be a viable starter in a league that clearly lacks them, and he's capable of managing games well enough to avoid losing them for his side, but he's far too injury-prone to be more than a short-term solution under center.

There are way too many red flags here for an organization to feel comfortable with committing millions of dollars for an extended amount of years to the 30-year-old. Any team courting Bradford should beware.

Editor's Note: Sam Bradford intends to sign a 1-year, $20 million contract with the Arizona Cardinals.

The future once looked exceedingly bright for Allen Robinson, but the promising wide receiver has hit a rough patch in his career. There's still a decent chance he pans out as one of the game's top wideouts, but it's far from guaranteed after the past two years. Robinson missed nearly the entire 2017 campaign after tearing his ACL early in the opener, an unfortunate follow-up to an underwhelming 2016 season.

A second-round pick in 2014, Robinson put together a respectable rookie outing, catching 48 passes for 548 yards and two touchdowns in 10 games (he was shut down with a stress fracture in his foot). But it was his sophomore showing that turned heads. The Penn State product put himself on the map by playing in all 16 of the Jacksonville Jaguars' contests, racking up 80 receptions on 153 targets for 1,400 yards and 14 touchdowns.

Expectations were high the following year, but Robinson wasn't able to live up to them. Although he remained healthy and garnered nearly the same amount of targets (151) and catches (73), the 6'3", 211-pound receiver only generated 883 yards and six touchdowns.

Many projected a bounce-back year in 2017, but Robinson suffered the non-contact ACL injury on his first and only catch of the year. The injury kept him sidelined throughout Jacksonville's remarkable run to the AFC Championship Game, which may be a key reason the franchise is comfortable with letting its former No. 1 receiver test the open market.

The Jags declined to apply the franchise tag to Robinson, which would have paid him close to $16 million for the upcoming campaign. The 2015 Pro Bowler is the top available free agent at his position—a class that also includes teammates Marqise Lee and Allen Hurns—and should be in line for a mega contract despite his injury woes.

On the plus side, Robinson hasn't suffered any setbacks and appears well on his way to a full recovery. He should be back on the field in time for OTAs this spring and hopefully won't be negatively affected by the ACL tear going forward. Still, Robinson has only one spectacular season under his belt but will be almost surely be paid top dollar for his services.

It's far from certain he will be able to produce his 2015 numbers on a regular basis even if he returns to full health. If he winds up consistently performing around his 2016 level, the deal he signs will be a poor investment.

Editor's note: Allen Robinson intends to sign a 3-year, $42 million contract with the Chicago Bears. 

There aren't many two-time Pro Bowl running backs on the open market this year, which is why Doug Martin should attract at least a couple of suitors in the coming weeks. The Muscle Hamster was cut loose after six seasons with the Tampa Bay Buccaneers, who passed on paying him close to $7 million for the 2018 season after a significant dip in his production in recent years.

He missed time at the end of 2016 and the beginning of 2017 as a result of a performance enhancing drug suspension and lost his starting job to Peyton Barber down the stretch because of a combination of poor play and the aforementioned misconduct. The PED violation allowed the Bucs to move on without having to pay him any remaining guaranteed money.

Martin appeared poised for stardom after being selected in the first round of the 2012 draft. He rushed for 1,454 yards and 11 touchdowns on 319 attempts as a rookie, but he took a step back in the following two injury-marred campaigns. The Boise State product re-emerged in 2015 with a 1,402-yard, six-touchdown outing that saw him finish second to Adrian Peterson for the league's rushing title and earn both Pro Bowl and first-team All-Pro honors.

That performance helped him land a five-year, $35.75 million contract extension with $15 million guaranteed, but he never attained that level of success again. His yards-per-carry average was below 3.0 over the past two seasons, opening the door for Barber, Charles Sims and Jacquizz Rodgers to cut into his workload.

As a 29-year-old running back with high mileage, Martin will be hard pressed to find anything close to that kind of coin in free agency. The Oakland, California, native may opt to try to sign with a contender after never getting a chance to participate in a postseason matchup during his time in Tampa, Florida.

If rejuvenated, he could still contribute to a running back-needy squad, but that team will need to protect itself with an incentive-laden contract in order to avoid getting burned. There's a good chance this player's best days are behind him and that he will never replicate the elite form he once showcased.

There are some players who are special but can't seem to find their way on to the field on a consistent basis because of consistent injuries.

Tyler Eifert is one of the game's great tight ends when healthy, but his career has been pockmarked by ailments that have severely limited his production since the Cincinnati Bengals selected him in the first round back in 2013. The 27-year-old has played in only 39 of a possible 80 regular-season contests during his NFL career.

Eifert's best season was the 2015 campaign, when he hauled in 52 receptions for 615 yards and 13 touchdowns, earning Pro Bowl honors in the process. It was also one of his most healthy years, as he played in 13 games—the most since his rookie year, during which he only missed one matchup.

The Bengals decided to pick up the Notre Dame product's fifth-year option after that season, but he wasn't able to carry any momentum forward. Eifert only participated in eight games during the 2016 season, which got off to a late start as he rehabbed from the ankle injury he suffered in the previous campaign's Pro Bowl. It was also cut short because of a lingering back issue. Things got even worse last year, as he played in just two games and landed on injured reserve after undergoing back surgery for the second straight season.

Any team interested in Eifert will be taking a huge gamble on his health. While the 6'6", 255-pound tight end says he has recovered, recently telling Jim Owczarski of the Cincinnati Enquirer "everything is fixed," he's never shown a penchant for staying upright for long.

Still, the allure of his immense talents could be impossible for organizations to ignore. There is no tight end on the open market this year even close to being as dynamic and skilled as he is, let alone one who has established himself as one of the best overall players at his position when he's at or close to 100 percent.

Eifert has a nose for the end zone, scoring on 20 of his 127 receptions, and he could still be in line for a humongous contract despite his injury issues. Most top tight ends of his caliber are making over $9 million per season, a price that would be devastating to pay if he can't suit up on a regular basis.

Injuries may bring his value down a bit, but Eifert will still get paid well this offseason. The club that signs his checks will stake its success on his ability to stay healthy, which history has shown to be a risky undertaking.

The New York Jets officially parted ways with Muhammad Wilkerson on Feb. 28 after the defensive end spent seven seasons with the franchise, recording 44.5 sacks during that span.

His production has fallen off a cliff recently, a dip that coincided with a massive payday. It wasn't too long ago that Wilkerson was thought of as cornerstone of the organization, and his contributions were rewarded with a five-year, $86 million (with $53 million guaranteed) extension in the 2016 offseason. The deal turned out to be a nightmare for the Jets, as the Temple product tallied just eight sacks and countless more headaches over the following the two years.

Wilkerson's work ethic and production were close to nonexistent after cashing in, as there were numerous reports the 28-year-old was regularly late to team events and sometimes didn't show up to meetings. He appeared to be going through the motions on and off the field, which is why the Jets elected to cut ties with the New Jersey native rather than pay him nearly $17 million—saving $11 million in cap space, per Spotrac—in 2018.

Despite his transgressions, Wilkerson will have a plethora of suitors on the open market. Teams will remember his better days, including the 12-sack season he put together in 2015 that was pivotal in earning his big contract extension. At 6'4" and 315 pounds, and in possession of a first-round pedigree and a resume that features plenty of highs to go along with his recent lows, it's only a matter of time before an organization talks itself into paying Wilkerson a hefty sum to play football in its colours this coming season.

The Green Bay Packers are one of those clubs the defensive lineman scheduled a visit with, per Tom Silverstein of the Milwaukee Journal Sentinel, and it wouldn't be surprising if Wilkerson once again works with Mike Pettine, the former Jets defensive coordinator who recently took on the equivalent role in Green Bay. Mo had a great season under Pettine in 2012, racking up 69 tackles, five sacks, four pass defenses and three forced fumbles in his sophomore campaign.

There's a chance Wilkerson rehabilitates his career away from New York, but any franchise willing to roll the dice here should tread carefully. The former Pro Bowler is immensely talented but hasn't shown a willingness to play at a high level in years.

If the desire returns, there could be a great return on the investment. But that is far from a sure thing. Consider this talented but troubled lineman the biggest red flag of the 2018 NFL free-agency class.