NFL free agency preview: 16 best players to keep an eye on

FOX Sports Senior NFL Writer Alex Marvez takes a look at the top 16 unrestricted free agents headed into the 2016 offseason. (Note: Some of these names will never hit the market because of contract extensions with their current teams or the franchise tag designation.)

1: Denver outside linebacker Von Miller
Franchise/transition tag possibility without contract extension:
High.

Having rebounded from an NFL drug suspension and serious knee injury earlier in his career, Miller continued his monster 2015 regular season by being the most dominant pass-rusher throughout the playoffs en route to winning Super Bowl 50 MVP honors. The Broncos will not let him walk away.

2: Carolina cornerback Josh Norman
Franchise/transition tag possibility without contract extension:
High.

The Panthers reportedly offered Norman a contract extension worth $7 million annually entering the 2015 season. Norman declined the offer thinking he was worth more, which is a decision about to pay huge dividends. Norman is now considered an elite-level cornerback who is expecting a contract to reflect such standing. If the Panthers don't reach Norman's financial demands, he is line for a franchise tag projected in the $14-million range for the 2016 season.

3: New York Jets defensive end Mo Wilkerson
Franchise/transition tag possibility without contract extension:
High.

Even though they chose Leonard Williams with the No. 6 overall pick in last year's draft, the Jets aren't about to let one of the top defensive ends leave even if it means having to use a franchise tag in the $16M ballpark on Wilkerson for the 2016 season.

4: Kansas City safety Eric Berry 
Franchise/transition tag possibility without contract extension:
High.

Berry has gradually regained the form that made him one of the NFL's top safeties before being diagnosed in December 2014 with Hodgkin Lymphoma. The franchise tag for a safety (approximately $11 million) is the cheapest of any defensive position, which makes using it a viable option if Kansas City can't reach agreement on a new contract.

5: Washington quarterback Kirk Cousins
Franchise/transition tag possibility without contract extension:
Likely.

There is virtually no chance Washington lets Cousins walk after he blossomed when given the starting nod ahead of Robert Griffin III for the 2015 season. The bigger question is whether the Redskins and his agents can come to agreement on how much Cousins is worth. He hasn't proven worthy of "elite" quarterback money yet and may never hit the heights of Tom Brady, Aaron Rodgers et al. Cousins also might not be as successful if playing in another team's offense. But having to use a franchise tag in the $20M dollar range to insure keeping Cousins in the fold for at least one season isn't an appealing option for Washington under the salary cap either.

6: Tampa Bay running back Doug Martin
Franchise/transition tag possibility without contract extension:
Doubtful.

Because of injuries that limited him to 17 of a possible 32 games the previous two seasons, the Buccaneers decided against exercising a $5.6 million contract option on Martin for the 2016 season. Martin will be more expensive to keep now that he rebounded in 2015 with 1,402 rushing yards -- the NFL's second-highest total behind Minnesota's Adrian Peterson (1,485) -- while appearing in all 16 contests.

7: San Diego safety Eric Weddle
Franchise/transition tag possibility without contract extension:
None.

The relationship between Weddle and the Chargers gradually disintegrated after he was unable to reach agreement on a contract extension heading into the final year of his deal. Weddle wants out after nine seasons in San Diego and the Chargers appear ready to comply. "He's stated he's ready to move on," general manager Tom Telesco told Chargers media last month. "For all parties involved, that's probably (for) the best."

8: Denver quarterback Brock Osweiler
Franchise/transition tag possibility without contract extension:
Unlikely.

It will be now or never for the Broncos to deem Osweiler their starting quarterback and take the necessary steps to install him as such. That means saying goodbye to 39-year-old Peyton Manning, whose release would clear $19 million under the salary cap that could be funneled toward Osweiler's new contract.

9: Philadelphia quarterback Sam Bradford
Franchise/transition tag possibility without contract extension:
Unlikely.

Predicting his future is difficult with the Eagles having made major changes in the front office and at head coach with the firing of Chip Kelly, who brought Bradford to Philadelphia last March in a trade with St. Louis. While his 2015 production was erratic, that may have stemmed more from Bradford not being an ideal fit in an up-tempo attack that sputtered across the board. Bradford could excel in the more conventional West Coast-style system the Eagles are expected to use this season under new head coach Doug Pederson, but are the Eagles willing to pay the price to keep him -- and does Bradford even want to return?

10: Denver defensive end Malik Jackson
Franchise/transition tag possibility without contract extension:
None.

Like fellow 3-4 end Jaye Howard in Kansas City, Jackson is an under-the-radar standout at his position with the hard-to-find combination of pass-rush and run-stuffing skills. Denver's recent re-signing of end Derek Wolfe could be an indication that the Broncos are prepared to lose Jackson in free agency, especially with keeping outside linebacker Von Miller and quarterback Brock Osweiler as higher priorities.

11: Seattle outside linebacker Bruce Irvin 
Franchise/transition tag possibility without contract extension
: Low.

Irvin is comfortable enough in Seattle that he told Seahawks media last month that he would take "$3 million to $5 million" less than market value over the length of a long-term contract extension. If a deal can't be crafted, Irvin won't be lacking suitors in need of a pass-rush specialist. Among the teams in that boat are Jacksonville and Atlanta, both of which are coached by two of his former Seahawks defensive coordinators in Gus Bradley and Dan Quinn respectively.

12: Chicago wide receiver Alshon Jeffery
Franchise/transition tag possibility without contract extension:
Doubtful.

After two straight seasons of 1,100-plus receiving yards, Jeffery's production dipped in 2015 when he missed seven games because of injury. It would cost the Bears $13 million-plus to use the franchise tag on Jeffery. This could dissuade Chicago from doing so, especially with 2015 first-round draft pick Kevin White expected to return from a leg injury that sidelined the wideout for his entire rookie campaign. Even though there is a long history of money wasted on high-paid wide receiver signings in free agency, Jeffery's speed and penchant for big plays will draw him a huge offer elsewhere if he's available.

13: New York Jets quarterback Ryan Fitzpatrick
Franchise/transition tag possibility without contract extension:
Doubtful.

While not an All-Pro by any means, Fitzpatrick was the best quarterback New York fielded since Chad Pennington enjoyed a 22-touchdown, six-interception campaign in 2002. Fitzpatrick is a great fit working under Jets offensive coordinator Chan Gailey, who is his former head coach in Buffalo. That relationship should prompt the 33-year-old Fitzpatrick to re-sign rather than seek a contract from what would be his seventh different NFL team in 12 seasons.

14: Miami defensive end Olivier Vernon
Franchise/transition tag possibility without contract extension:
High.

The Dolphins made three big contract moves last offseason when signing Ndamukong Suh in free agency and extending the deals of quarterback Ryan Tannehill and center Mike Pouncey. The next big one is retaining Vernon, who led Miami with 7.5 sacks after top pass-rusher Cameron Wake went down at midseason with a torn Achilles tendon.

15: Chicago running back Matt Forte
Franchise/transition tag possibility without contract extension:
Extremely low.

Trying to forecast the market for a 30-year-old running back isn't easy, especially in Forte's case. His durability is evident by having only missed eight games in eight seasons, but Forte's total number of touches (2,522 combined rushing and receiving) comes with a heavy physical toll. If the Bears can't re-sign him, 2015 fourth-round pick Jeremy Langford appears ready to replace him. Those would be big shoes to fill. Forte would leave Chicago as the second-most statistically productive running back in franchise history behind the iconic Walter Payton.

16: Seattle left tackle Russell Okung
Franchise/transition tag possibility without contract extension
: Doubtful.

Since head coach Pete Carroll and general manager John Schneider arrived in 2010, the Seahawks have signed only one veteran offensive lineman (center Max Unger) to a big-money contract. The Seahawks must decide whether Okung should become the second with his six-year rookie contract expiring or else they need to find a new blindside protector for quarterback Russell Wilson. Okung's stock isn't helped by having already gone offseason shoulder surgery.

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