You know what they say: Age is just a number. Truthfully, though, when it comes to NFL players, Father Time is undefeated. The question is, when will the clock strike midnight on a guy being past his prime?
But I believe there are several impending free agents on the "wrong" side of 30 who still have some gas left in the tank. In this installment of the Schein Nine -- with free agency opening at 4 p.m. ET on Thursday -- I've compiled a list of veterans set to hit the market who absolutely can help your team this fall.
1) Calais Campbell, defensive end
Campbell, who'll turn 31 just before the start of next season, is still a strong and versatile player, as well as a team leader. He's been a rock for the always-stout Cardinals defense and a gem in the locker room, on the practice field and in the community, as well. Campbell is still a fine defensive lineman who can play (and has played) in all defensive schemes.
The 6-foot-8, 300-pounder posted his typical production in 2016: 53 tackles, eight sacks, six pass deflections, two forced fumbles and even a pick. With his hulking size and powerful game, Campbell's a problem for opposing offenses. Honestly, he's one of my favorite players in the league.
2) Brandon Marshall, wide receiver
The Jets are rightly in rebuilding mode. So, in a move that makes sense for the player and the team, New York gave Marshall his desired release last week. Don't let last year -- a chaotic campaign in Florham Park -- fool you: Brandon Marshall is still a legit No. 1 receiver. Sure, Marshall slumped by his own lofty standards, with 59 catches for 798 yards and three touchdowns. But the Jets didn't have a legit quarterback or O-line. Eric Decker was lost to injury in September and Marshall was consistently doubled. In 2015, Marshall had arguably the best receiver season in Jets history with 109 catches and 1,502 yards and 14 touchdowns, thus creating the illusion that Ryan Fitzpatrick was a viable starting quarterback. (That's a pretty impressive trick.)
3) DeSean Jackson, wide receiver
Jackson is 30, but he can still burn you. Need proof? His 17.9 yards per reception led the NFL this past season, the third time in his career Jackson has paced the league in that crucial category. This cat specializes in taking the top off a defense. Therefore, the Redskinsshould be all-in to bring him back. But if they aren't ...
A return to the Bay Area, where Jackson played his college ball, makes sense, as the 49ers certainly need receiver help. A reunion with the Eagles adds up, as well. Another logical move: heading home to Los Angeles to continue playing under his offensive coordinator of the last three seasons, new Rams head coach Sean McVay.
4) Andrew Whitworth, offensive tackle
At age 35, Whitworth remains an O-line rock at left tackle. I can't imagine why Cincinnati would let him get away. The Bengals spent their top two picks in the 2015 draft on tackles Cedric Ogbuehi and Jake Fisher, but neither has shown the ability to replace Whitworth on the blind side. A first-team All-Pro in 2015, Whitworth notched his third Pro Bowl bid this past season. Marvin Lewis says he's optimistic the Bengals will re-sign the vet, but nothing's guaranteed when a player hits the open market.
5) Pierre Garcon, wide receiver
Garcon's not a WR1 at this stage in his career, but he has a lot left to offer as a viable No. 2. In his age-30 season, Garcon just put up 79 catches for 1,041 yards. Nothing to sneeze at.
6) LeGarrette Blount, running back
Blount just shattered his previous career high with 334 carries (including the postseason), but he's still under 1,200 totes for his career. So, yes, I think there's gas left in this tank.
7) Lorenzo Alexander, outside linebacker
Alexander just enjoyed a breakout campaign at age 33, sacking the quarterback 12.5 times. Heck, Alexander totaled just nine sacks over his first nine NFL seasons combined. But Alexander's always had the reputation of being a sensational worker and teammate, dating back to his utility days on defense and special teams for the Redskins. Here's hoping the Bills reward him with a new deal. But if they don't, Alexander should have some interested suitors.
A backup for most of his career, Alexander doesn't have the wear and tear that most NFL players encounter in their 30s. And he's the type of character guy you want on your football team.
8) Nick Mangold, center
The classy Mangold was a great player and leader for 11 seasons on the team that drafted him. And while the rebuilding Jets cut him for cap space, there is no doubt in my mind Mangold still has a few more strong and sturdy years left. Yes, he missed half of last season due to ankle issues, but that was the first time in his career that he missed substantial time for injury.
9) Dwight Freeney, defensive end
Freeney is a future Hall of Famer in my book. He isn't that player anymore. But that swim move still works and strikes fear in opposing quarterbacks. Freeney is 37. Retirement is his next step. Chances are he won't sign with an NFL team until August. But he's still a pro's pro, and his mentorship cannot be overlooked. Look at how Vic Beasley blossomed -- leading the NFL with 15.5 sacks -- with Freeney taking him under his veteran wing.
Freeney helped Arizona in 2015, Atlanta last year. Wouldn't it be something if he went home to Indy to finish off his career? Or if the Connecticut native went home to New England?