Since the calendar turned to May, the NFL free-agent market has shifted and slowed. Only eight unrestricted free agents have been signed since May 10 and veteran cap casualties will become more part of the mix over the next few weeks.

Some players on my list below are recovering from injuries, so they might not be signed until just before the start of training camp.

Here are the NFL's top free agents.

1. Greg Hardy, defensive end

No team is making moves on him, and it might take some time before Hardy gets a chance to get back in the league. His agent, Drew Rosenhaus, got word out to teams that Hardy underwent 24 therapy sessions to improve his behavior. Teams are treating Hardy as though he's toxic. Nevertheless, he's a talented defensive force, and at age 27, he's still in his prime. Getting closer to camps, some team in need of a defensive playmaker may start dialing the phone.

2. Ryan Fitzpatrick, quarterback

No wonder Geno Smith was snippy with Jets reporters on Wednesday when they asked the expected questions about when Fitzpatrick will rejoin the team. Smith holds down the starting quarterback job at the moment, but all he hears are his teammates publicly campaigning for Fitzpatrick's return. After leading the New York Jets to a 10-win season in 2015, Fitzpatrick's greatest value is with the Jets. For other teams, he would be a backup. The Jets need to get Fitz signed before the start of training camp so the offense can be whole again.

3. Donte Whitner, safety

You figure the first team that suffers an injury at the starting strong safety position will sign Whitner. He's 30. He's productive. He's a leader. He would also be a great addition to a young secondary needing a mentor. The Los Angeles Rams looked at him, and that would have been a nice fit. He can come into a facility, study the playbook and be a plug-and-play starter.

Donte Whitner has made three Pro Bowls in his career. Nick Cammett/Diamond Images/Getty Images

4. Dwight Freeney, defensive end

He visited the Cincinnati Bengals this week and will meet with the Atlanta Falcons next week. Last season, the Arizona Cardinals called him on the week he was considering putting in his retirement papers. Freeney responded with eight sacks in 11 regular-season games. He might have more value as a pass-rusher in a 4-3 scheme than being an outside linebacker in a 3-4. Regardless, he still has something left in the tank, and he still wants to play.

5. Arian Foster, running back

Foster says he needs about another month of recovery to be fully ready to serve a team in its backfield. He's coming off an Achilles tendon tear. Foster turns 30 in August and teams shy away from signing older running backs. His situation is much like Chris Johnson's last year. Johnson waited forever until the Cardinals signed him, and he responded with great numbers (814 yards in 11 games). Once he's healthy, Foster is an intriguing option for a team looking for a proven running back.

6. Louis Vasquez, guard

It still baffles me that Vasquez hasn't found a home. He's a 29-year-old guard who has missed only one start in the past four seasons. Injuries have nagged him for the past couple years and he may not have been the right fit for Gary Kubiak's zone-blocking scheme in Denver. His situation is much like Evan Mathis' from a year ago. He seemingly waited forever until the Denver Broncos signed him.

7. Anquan Boldin, wide receiver

The San Francisco 49ers elected not to bring back Boldin, but he's one of the most physical receivers of his era. Even at 35, he's good enough to catch between 65 and 80 passes. He's a perfect fit for a playoff team in need of a tough receiver who can lead.

Anquan Boldin can still be a productive NFL receiver. AP Photo/Tony Avelar

8. Brian Hartline, wide receiver

It's no surprise that the Cleveland Browns released Hartline this week. They drafted five wide receivers and are trying to get younger. At 29 years old, Hartline still has 70-catch potential. He's a decent option for a team looking for a dependable 6-foot-2, 200-pound pass-catcher.

9. Chris Culliver, cornerback

Were it not for his Week 2 suspension for personal conduct, Culliver would still be a member of the Washington Redskins. That suspension voided an $8 million guarantee for 2016. It allowed the Redskins to sign Josh Norman and cut Culliver. The 27-year-old is coming off ACL surgery, but he was one of the top free agents in 2015. Once healthy, Culliver can offer a team a starting cornerback option.

10. Leon Hall, cornerback/safety

Injuries have hurt Hall of late. He has had two Achilles tears during his nine-year NFL career and he underwent back surgery after the season. As a cornerback at the age of 31, he would help more in the slot. Had the Bengals brought him back, they were thinking of using him at safety.

11. Mike Neal, defensive end/linebacker

Neal still can't figure out why the Green Bay Packers didn't re-sign him. He had four or more sacks in each of the past four years and had been a productive player in his six seasons in Green Bay. Neal has told people he may have been negatively affected by the Al Jazeera story linking him to performance-enhancing drugs. In fact, the league is going to interview him soon. As player, he was good enough to be on the field for 750 plays as linebacker last season for the Packers.

Mike Neal's availability may be a result of PED allegations from late last year. Jeff Haynes/AP

12. Amini Silatolu, guard

The Cardinals. 49ers and Seattle Seahawks looked at Silatolu during the offseason but elected not to sign him. He's coming an an ACL tear in November and may need more time to convince a team to put him on the roster. When healthy, he's a 6-foot-4, 320-pound powerful guard who can help a running attack.

13. Tarvaris Jackson, quarterback

The Seahawks want him back as a backup to Russell Wilson, but, like last year, Jackson has elected to wait until the market comes to him. More teams are going with younger backup quarterbacks these days, but Jackson remains perhaps the top veteran backup on the market.

14. Andre Roberts, wide receiver

Recently cut by the Washington Redskins, Roberts is a good slot receiver who was able to get a contract for $4 million per year in 2014. His numbers have dropped over the past four years, but if he can get to the right offense, he can catch 50 to 60 passes for an 11- to-12-yard average.

15. Walter Thurmond, safety

Until he officially announces his retirement, I'll keep Thurmond's name on the list. He received interest at the start of free agency, but word got out that he was considering retirement. He's a smart defensive back who fits at both safety and slot cornerback.