Le'Veon Bell, RB*
Age: 25
Previous team: Pittsburgh Steelers
Key 2016 stats: 261 carries, 1,268 rushing yards, 4.9 yards per carry, seven touchdowns, 88.3 PFF grade
One thing to know: The Steelers tagged Bell early in the offseason and some think they may still try to agree to a long-term deal for one of the league's most versatile running backs.
Kirk Cousins, QB*
Age: 28
Previous team: Washington Redskins
Key 2016 stats: 4,917 yards, 67% completion, 25 touchdowns, 12 interceptions, 85.9 PFF grade
One thing to know: Cousins was also hit with the franchise tag, and he and the Redskins are reportedly still talking about long-term contracts. But according to MMQB's Albert Breer, the 'Skins don't seem sold on Cousins as the QB of the future.
Melvin Ingram, LB*
Age: 27
Previous team: San Diego Chargers
Key 2016 stats: Eight sacks, four forced fumbles, 88.1 PFF grade
One thing to know: The Chargers have said they also want to come to long-term deal with Melvin Ingram. Ingram was Pro Football Focus' sixth-highest graded edge defender in 2016.
Kawann Short, DT*
Age: 28
Previous team: Carolina Panthers
Key 2016 stats: Six sacks, one forced fumble, 87.7 PFF grade
One thing to know: Despite a dropping from 11 sacks in 2015 to six in 2016, Short still figures to be a big part of a Panthers' pass rush that ranked fifth in sacks.
Chandler Jones, DE*
Age: 27
Previous team: Arizona Cardinals
Key 2016 stats: 11 sacks, four forced fumbles, two fumble recoveries, 87.4 PFF grade
One thing to know: Despite fairly gaudy stats, Jones said last year was a learning curve for him and he expects to be better in a second season with Arizona.
Jason Pierre-Paul, DE*
Age: 28
Previous team: New York Giants
Key 2016 stats: Seven sacks, three forced fumbles, one touchdown, eight fingers, 86.2 PFF grade
One thing to know: The Giants hit JPP with the franchise tag, despite Pierre-Paul saying he no longer wants to play on one-year deals and prove he can play with a damaged hand. The two sides are likely working on a long-term deal.
Trumaine Johnson, CB*
Age: 27
Previous team: Los Angeles Rams
Key 2016 stats: Eight pass defenses, two interceptions, 81.0 PFF grade
One thing to know: According to ESPN, Johnson is the first cornerback to be tagged in back-to-back years since Charles Woodson in 2004 and 2005.
Dont'a Hightower, LB
Age: 26
Previous team: New England Patriots
Key 2016 stats: 65 tackles, 2.5 sacks, one forced fumble, 85.7 PFF grade
One thing to know: Though it doesn't always show up in stats, Hightower's play was reportedly one of the reasons the Patriots traded Jamie Collins last year. Keeping Hightower may be expensive.
Brandon Williams, NT
Age: 28
Previous team: Baltimore Ravens
Key 2016 stats: 51 tackles, one sack, 75.9 PFF grade
One thing to know: Williams topped ESPN's list of 150 free agents. The former Division II lineman has become one of the top nose tackles in the NFL.
Alshon Jeffery, WR
Age: 27
Previous team: Chicago Bears
Key 2016 stats: 52 caches, 821 yards, two touchdowns, 77.6 PFF grade
One thing to know: Jeffery has struggled with injuries, inconsistent quarterback play, and a PED suspension in 2016. But if healthy, with a capable quarterback, he could be dynamic wide receiver.
Calaise Campbell, DT
Age: 30
Previous team: Arizona Cardinals
Key 2016 stats: Eight sacks, two forced fumbles, one interception, 90.4 PFF grade
One thing to know: The Cardinals are reportedly unlikely to re-sign Campbell, PFF's second highest-graded interior defender. The Broncos are rumored to be interested in him.
Kevin Zeitler, G
Age: 26
Previous team: Cincinnati Bengals
Key 2016 stats: 87.1 PFF grade
One thing to know: CBS's Joel Corry, a former NFL agent, said he expects Zeitler to "break the bank" for teams pursuing him.
A.J. Bouye, CB
Age: 25
Previous team: Houston Texans
Key 2016 stats: One sack, one interception, 16 pass defenses, 90.9 PFF grade
One thing to know: Bouye went from fourth on the Texans' cornerback depth chart to one of the premier cornerbacks in the league. He'll likely receive a giant contract this offseason.
Stephon Gilmore, CB
Age: 26
Previous team: Buffalo Bills
Key 2016 stats: Five interceptions, 73.2 PFF grade
One thing to know: As Gilmore's PFF grade suggests, he had some coverage issues, despite his high interception count. He may still get typical top-cornerback pay because of his ball-hawking ways and physical gifts.
T.J. Lang, G
Age: 29
Previous team: Green Bay Packers
Key 2016 stats: 87.0 PFF Grade
One thing to know: According to Yahoo's Charles Robinson, Lang is expected to make $8-10 million per season on his next contract.
Martellus Bennett, TE
Age: 29
Previous team: New England Patriots
Key 2016 stats: 55 catches, 701 receiving yards, seven touchdowns, 79.8 PFF grade
One thing to know: Bennett played a crucial role for the Patriots, stepping up when Rob Gronkowski went down with a back injury. Will the Patriots spend big to keep Bennett as insurance for oft-injured Gronk?
Dontari Poe, NT
Age: 26
Previous team: Kansas City Chiefs
Key 2016 stats: 55.8 PFF grade
One thing to know: Poe is remarkably athletic for a 3456-lb lineman. Any team that signs him will also get a big man who get into the end zone, too!
Terrelle Pryor, WR
Age: 27
Previous team: Cleveland Browns
Key 2016 stats: 77 catches, 1,007 receiving yards, four touchdowns, 78.6 PFF grade
One thing to know: The quarterback-turned-wide-receiver had the best season of his career in 2016. The Browns have said they'd like to keep him, but no one is irreplaceable on a one-win team.
Tony Jefferson, S
Age: 25
Previous team: Arizona Cardinals
Key 2016 stats: 96 tackles, two sacks, two forced fumbles, 88.6 PFF grade
One thing to know: NFL Network says Jefferson outplayed the more heralded Tyrann Mathieu last season, proving to be a hard-hitter who can defend the run and pass. He's likely to out-price the Cardinals.
Andrew Whitworth, OT
Age: 35
Previous team: Cincinnati Bengals
Key 2016 stats: 91.3 PFF grade
One thing to know: After posting PFF's second highest grade for an offensive tackle, Whitworth said he's keeping all of his options open, but would like to join a Super Bowl contender next season.
DeSean Jackson, WR
Age: 30
Previous team: Washington Redskins
Key 2016 stats: 56 catches, 1,005 receiving yards, four touchdowns, 77.0 PFF grade
One thing to know: Though he's injury-prone, Jackson proved last season that he still has burst and playmaking ability, even at 30 years old. There's been chatter about Jackson having a reunion with the Eagles this offseason.
Larry Warford, G
Age: 25
Previous team: Detroit Lions
Key 2016 stats: 81.5 PFF grade
One thing to know: Warford is expected to earn a big contract, and the Lions already preparing for his departure, according to the Detroit Free Press.
Johnathan Hankins, DT
Age: 24
Previous team: New York Giants
Key 2016 stats: 47.1 PFF grade
One thing to know: After signing Damon Harrison to a big contract last summer, Hankins may be leaving the Giants this offseason.
Ricky Wagner, OT
Age: 27
Previous team: Baltimore Ravens
Key 2016 stats: 84.5 PFF grade
One thing to know: According to NFL.com's Mike Garafolo, Wagner is expected to "blow the lid" off the right tackle market and generate a lot of interest.
Jabaal Sheard, DE
Age: 27
Previous team: New England Patriots
Key 2016 stats: Five sacks, 79.6 PFF grade
One thing to know: After signing with the Patriots on a two-year deal in 2015, Sheard may have played himself into a bigger deal elsewhere.
Logan Ryan, CB
Age: 26
Previous team: New England Patriots
Key 2016 stats: 92 tackles, one forced fumble, two interceptions, 83.5 PFF grade
One thing to know: The Patriots may have to let go of Ryan with his counterpart, Malcolm Butler, also set for a pay day.
T.J. McDonald, S
Age: 26
Previous team: Los Angeles Rams
Key 2016 stats: One sack, two interceptions, 75.3 PFF grade
One thing to know: According to reports, McDonald is likely to leave the Rams in free agency. NFL.com describes him as a "tone-setting" presence in the secondary with his big hits.
Brandon Marshall, WR
Age: 32
Previous team: New York Jets
Key 2016 stats: 59 catches, 788 receiving yards, three touchdowns, 71.7 PFF grade
One thing to know: Though he had a poor 2016 season, he's just one year removed from a 1,500-yard, 14-touchdown season in 2105. With a good quarterback, Marshall can still be an elite receiver.
Riley Reiff, OT
Age: 28
Previous team: Detroit Lions
Key 2016 stats: 67.5 PFF grade
One thing to know: Reiff posted a decent season switching from left tackle to right tackle. ESPN suggests he may leave the Lions if a suitor allows him to play left tackle.
Eddie Lacy, RB
Age: 26
Previous team: Green Bay Packers
Key 2016 stats: 71 carries, 306 rushing yards, 5.1 yards per carry
One thing to know: Lacy struggled with his weight in 2015, then got hurt early in 2016. He's still just 26, with only 788 career carries. He could have value to teams who believe his 1,000-yard first two seasons were the real Lacy when he's healthy.
Barry Church, S
Age: 29
Previous team: Dallas Cowboys
Key 2016 stats: 85 tackles, one forced fumble, two interceptions, 85.3 PFF grade
One thing to know: Church posted a career year in 2016 and helped a surprisingly stout Cowboys secondary. He may have several suitors this offseason.
Russell Okung, OT
Age: 29
Previous team: Denver Broncos
Key 2016 stats: 73.5 PFF grade
One thing to know: Okung negotiated his own contract with the Broncos last year, and it backfired, as the Broncos cut him after just one season. He was only okay last season, but may still have suitors this year as he's usually been a reliable force on the offensive line.
Latavius Murray, RB
Age: 27
Previous team: Oakland Raiders
Key 2016 stats: 195 carries, 788 yards, 12 touchdowns, 4.0 yards per carry, 73.1 PFF grade
One thing to know: Murray didn't post a great 2016 season, but he was still a high-volume scorer for a potent Raiders offense. With the ability to also catch passes, Murray could have several suitors.
BONUS: Tony Romo, QB
Age: 36
Previous team: Dallas Cowboys
Key 2016 stats: Three completions, 75% completion, 29 yards, one touchdown
One thing to know: Romo lost his job to Dak Prescott last season. He's not technically a free agent, but Romo may be the flashiest names on the trade market, as teams look for a veteran quarterback to push them over the top. How much Romo has left in the tank, however, is unknown.