NFL Free Agency 2017: Players Now in Danger of Losing Starting Roles

For every action, there is an equal and opposite reaction. Isaac Newton's third law of motion is a driving force in NFL free agency. 

The majority of acquisitions made at the beginning of the league's new year resulted in a team filling a need from another player being released, leaving to sign with another franchise or both.

There are other instances in which disappointing performances from starters forced organizations to upgrade their respective positions.

A glimmer of hope still exists for these once highly regarded individuals, yet their luster is starting to dull. 

Former first-round picks, fantasy darlings and reliable veterans are in jeopardy of losing their starting jobs because of recent free-agent signings.

Thomas Rawls, Seattle Seahawks

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Thomas Rawls was supposed to be Marshawn Lynch's heir apparent. Things didn't got as planned. 

As an undrafted rookie, Rawls exploded on to the scene with 830 rushing yards, including three 100-yard games and a 200-yard effort, filling in for an injured Lynch. Unfortunately, Rawls' first campaign came to an end when he suffered a fractured ankle.

The injury required a long recovery that prevented Rawls from returning to form in 2016. He only played nine games, making seven starts, and averaged 3.2 yards per carry.

Meanwhile, the Seattle Seahawks running attack fell apart without the now-retired Lynch behind a porous offensive line. In 2015, Seattle ranked third overall in rushing offense. The team faltered to 25th overall a year later.

Rawls still has an opportunity to become the the team's lead back, but the organization hedged its bets when it inked veteran Eddie Lacy to a one-year, $4.25 million deal. 

Lacy experienced the worst season of his career in 2016 because of an injured ankle, which forced him on to injured reserve. The former second-round pick managed only 360 yards in five games. But he ran for 3,075 yards during his first three years. Weight issues have plagued him, though, even through this free-agent courtship.

A fit Lacy, who returns to form, can still be a feature back. If not, Rawls will get another opportunity to carry the load.

Nelson Agholor, Philadelphia Eagles

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Everyone knew the Philadelphia Eagles needed to upgrade their wide receiver corps. The organization took the proper steps to ensure franchise quarterback Carson Wentz has the weapons around him to succeed. 

Philadelphia targeted and signed Alshon Jeffery and Torrey Smith at the start of free agency. With these acquisitions, the team's starting wide receiver corps is completely revamped. It needed to be too. 

Last season, the Eagles wide receivers were plagued by inconsistency and drops. Former first-round pick Nelson Agholor was a primary culprit.

His production hasn't been enough to overlook these issues, either. The USC product provided 59 receptions for 648 yards and three touchdowns in his two seasons. Pro Football Focus graded him as the NFL's worst wide receiver last year.

Agholor is the team's fourth receiver. Jeffery and Smith will be the team's starting bookends with Jordan Matthews out of the slot. He's Wentz's sixth or seventh option when tight end Zach Ertz, running back Darren Sproles and fellow receiver Dorial Green-Beckham are added to the mix. 

He must find a way to contribute or his career in Philadelphia could come to a unceremonious end sooner rather than later.

Zach Miller, Chicago Bears

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The Chicago Bears' Zach Miller is a good football player. Even so, the organization still wanted an upgrade at tight end.

Part of the reason is Miller's age. The Nebraska-Omaha product blossomed late in his career. In 2016, he finished third on the team with 47 receptions for 485 yards and tied for the lead with four touchdown catches. But he will turn 33 during the upcoming campaign. 

Dion Sims wasn't more productive last season. However, he's only 26. 

A three-year, $18 million contract doesn't indicate Sims will take a backseat to Miller. Instead, the opposite is expected to occur. 

What's particularly important about this trade-off is upgrading the run game. Yes, the Bears will want their tight tend to contribute in the passing attack and serve as a security blanket for new quarterback Mike Glennon. Miller isn't much of a blocker, though. 

Sims is a bigger—nearly 30 pounds heavier—more physical and better in-line blocker. With the offense built around last year's rookie sensation, Jordan Howard, a true two-way tight end became necessary.

Greg Robinson, Los Angeles Rams

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Greg Robinson never developed into the dominant blocker the Los Angeles Rams projected he would become when the organization used the second overall pick in the 2014 NFL draft to acquire the Auburn product. 

Of the 76 offensive tackles who qualified last season for Pro Football Focus' rankings, Robinson graded 70th overall. 

This is a far cry from the young man who obliterated collegiate defenders. He was raw at the time, but his physical tools and aggressive nature pointed toward a top prospect. Instead, he struggled to pick up the intricacies and technique needed to succeed at left tackle.

The same can't be said of Andrew Whitworth. 

Whitworth is an 11-year veteran who is still at the top of his game. While Robinson ranked among the worst blockers in 2016, the 35-year old graded among the top four offensive tackles in each of the past three seasons. As a result, the Rams signed him to a three-year, $33.75 million contract to protect quarterback Jared Goff's blind side.

Robinson, meanwhile, will move back to guard. He started his first five games at guard before being bumped outside to tackle, performing better during that stretch than at any other point in the past two seasons.

Cameron Erving, Cleveland Browns

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The Cleveland Browns' Cameron Erving is well on his way to being labeled a draft bust. 

In 2015, the organization spent the 19th overall selection on the versatile offensive lineman, who was named first team All-ACC as a senior at both left tackle and center.

His potential to play over the ball never fully developed, though. Too often, Erving provided the wrong type of highlight blocks. Defenders rag-dolled the Browns center at least once in almost every contest. The young lineman struggled immensely with his technique and recognition. In fact, he graded as the worst starting center in the league last season by a wide margin, per Pro Football Focus.

At the onset of free agency, the organization prioritized upgrades along its offensive interior. The team targeted and signed the top available center in the 26-year-old J.C. Tretter. The former Green Bay Packer, who signed a three-year, $16.75 million deal, graded among the league's best despite missing nine games through injury.

The team also made Kevin Zeitler the NFL's highest-paid guard when he signed a five-year, $60 million contract—which will also push veteran John Greco out of the starting lineup. 

With left tackle Joe Thomas, left guard Joe Bitonio, Tretter and Zeitler, the Browns need to solve right tackle. A competition against last year's third-round pick, Shon Coleman, to win the starting spot just might be Erving's last chance to prove himself in Cleveland.

Clinton McDonald, Tampa Bay Buccaneers

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Three years ago, the Tampa Bay Buccaneers went on a free-agent spending spree.

The team acquired cornerback Alterraun Verner, defensive end Michael Johnson, quarterback Josh McCown, offensive tackle Anthony Collins and defensive tackle Clinton McDonald. The organization also traded for Pro Bowl guard Logan Mankins. 

Only McDonald remains with the team, and his status is about to change after the team signed Chris Baker to a three-year, $15.75 million contract. 

Since becoming a member of the Buccaneers, McDonald has started 31 games as the team's 1-technique next to All-Pro 3-technique Gerald McCoy. His inconsistency, particularly during the 2016 season, proved to be problematic, though. McDonald isn't stout of the point of attack next to the disruptive McCoy. 

Instead, the Buccaneers searched for an upgrade against the run and found one in Baker. The 29-year-old defender is more than 20 pounds heavier than McDonald, stronger at the point of attack and quite difficult to move. He graded among the league's best run defenders in 2016, per Pro Football Focus. 

The Buccaneers signed McDonald to play under a different head coach and defensive scheme. His effectiveness became limited under defensive coordinator Mike Smith. As a result, the veteran defensive tackle will be reduced to a rotational role.

Ahmad Brooks, San Francisco 49ers

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Father Time never loses. Ahmad Brooks has been a stalwart in the San Francisco 49ers defense for nine seasons, but his time has passed.

Brooks just turned 33, and he's not an ideal fit in Robert Saleh's incoming scheme. Instead, the team is moving in another direction.

NaVorro Bowman will stalk the middle of the field. The organization signed Malcolm Smith as well. Smith's familiarity with the Seattle Seahawks-style system that will be implemented and production over the past two seasons make him Bowman's top running mate. 

Since the league's teams are in nickel the majority of the time, those two will be San Francisco's top linebackers.

The organization also re-signed Ray-Ray Armstrong and agreed to a deal with former Seahawk Brock Coyle. Those two are better athletes at this point in their respective careers compared to Brooks. As such, one of the two can serve as the third starting linebacker in the team's base look. 

Brooks started 91 games since the 2011 campaign. He played well, but he did so in a completely different defense than the one that is about to be installed. He can still be effective even though his role will almost certainly be minimized.

Da'Norris Searcy, Tennessee Titans

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Two kinds of safeties exist. There are free safeties, who cover plenty of space in the passing game. Meanwhile, strong safeties are better near the line of scrimmage against the run. 

These generalities faded for a time because of the preponderance of Cover 2. However, the differentiation between these positions reappeared as defensive coordinators found creative ways to use both skill sets. 

When an organization signs a free agent who overlaps with the previous starter, the incumbent knows his time is limited. 

Da'Norris Searcy started 14 games as the Tennessee Titans' strong safety in 2016. The 28-year-old defensive back played relatively well, with 51 total tackles and eight defended passes, but the Titans couldn't pass on a chance to sign a top free-agent safety. 

The organization agreed to a four-year, $25 million contract with Johnathan Cyprien. Like Searcy, Cyprien is a physical box defender. Cyprien is three years younger and a true tone-setter, though. Last year, the Florida International product led all safeties with 128 tackles. 

Tennessee made it a priority to upgrade its secondary. With Cyprien alongside fellow addition Logan Ryan, the Titans are much better along their back line. A player like Searcy must simply step aside after such upgrades.