Each year, between 400 and 500 NFL players enter the offseason without contracts. But between 200 and 300 are added to the league each year either via the draft or as undrafted free agents. That means that, even after some guys have retired under their own power, there are still 100 to 200 guys who simply never get signed.
Injuries happen and spots open up throughout the year. Some stay out of football for a season. Some are dealing with their own injuries and re-enter the sweepstakes the following spring.
But some simply fade away, never taking another NFL snap.
Here are 10 notable NFL veterans who might be on the verge of suffering such fate.
It's not that Brian Urlacher doesn't have the ability to bring something to a team in need of depth at the linebacker position, but the question is whether the 34-year-old is willing to accept a bargain-basement offer to play what will likely be a diminished role.
Urlacher missed 10 tackles in 2012 and was rated by Pro Football Focus as the second-worst run-defending inside linebacker in football. Sure, he was dealing with knee problems, but there's a good chance nobody trusts him anymore.
The year Shaun Alexander turned 30, he ran for 716 yards on 207 carries (3.5 yards per carry). Michael Turner turned 30 last year before running for 800 yards on 222 carries (3.6 yards per carry).
Both players were cut after those age-30 seasons. Alexander went the entire 2008 offseason without finding a new job. He'd be signed midway through the following season by the Redskins, but he ran the ball only 11 times before his career came to an end.
Turner feels a lot like the next Alexander. He says he has "a lot left," but I'd argue otherwise.
After 12 seasons with the Pittsburgh Steelers, Casey Hampton has received little to no interest on the open market as a 35-year-old. He's not a three-down player and is no longer the consistent run stuffer he used to be.
Hampton says he wants to play two more years, but he'd be lucky to get a one-year deal as a secondary signing in this market.
I think Charles Woodson will wind up landing somewhere as an option at safety, but it's strange that several teams reportedly showed interest in the former Defensive Players of the Year early in March and now we're hearing almost nothing.
He started only seven games in 2012 and will turn 37 this season, and last we heard from him, Woodson was disappointed in the interest he had received on the open market. He says he's not retiring, but if nothing transpires in the next few months, he could change his mind and walk away.
The market hasn't emerged at all for former Defensive Player of the Year James Harrison, who turns 35 in May and has made just a single visit since he became a free agent three weeks ago.
Because Harrison can be used as a situational pass-rusher, and because he still had five sacks in his last seven games in 2012, I'd imagine someone will eventually take a chance on him. Still, Sports Illustrated's Peter King called Harrison the "coldest name" at the owners meetings.
With so many good offensive tackles in this year's draft and Jared Gaither, Eric Winston and Andre Smith still on the open market, it's hard to see anyone biting with a 33-year-old Bryant McKinnie.
The problem, in addition to the fact he's getting up there in age, is that McKinnie is a one-dimensional tackle who can only play the left side. Thus, he's not an ideal swing tackle.
There's still a chance he re-signs with the Ravens or takes a cheap one-year deal later in the offseason, but there's been little reported interest thus far.
Quentin Jammer is a name, but that's about it at this point. The 33-year-old vet has missed just three starts in 10 years, but he's getting no love on the free-agent market.
The former No. 5 overall pick may have had three interceptions last year, but he surrendered an AFC-high eight touchdown passes and took nine penalties, which was the third-highest total in the league.
If he doesn't return to the Chargers, Jammer might be done.
He celebrated his 32nd birthday last week, which doesn't make Jammal Brown a football corpse just yet. The problem is that he faces the same market-related issue Bryant McKinnie is dealing with.
On the bright side for Brown, he's a right tackle with plenty of experience on both sides. But the former All-Pro has missed two of the last four seasons due to serious injuries, and he struggled immensely when he was healthy in 2010 and 2011.
Brown hasn't been an effective starter in half a decade, so he's probably done.
Remember all of the hype surrounding Felix Jones when he entered the league as a first-round pick in 2008? Sure, it's been five full years now and he's well-established as a bust, but he's still only 25 years old.
As a free agent, though, Jones is receiving no reported interest on the free-agent market. He could still return to Dallas, but there's a belief that the Cowboys might rather draft or sign someone who is more reliable.
Jones' yards-per-carry average has declined in three of the four years since his electric rookie campaign.
Stanford Routt had some quality performances and good overall seasons during the first seven years of his career in Oakland, but the Raiders threw him overboard after a decent 2011 campaign and he hasn't been the same since.
Routt was torn apart so badly in coverage with Kansas City that he was released after only seven starts with the Chiefs, despite the fact he signed a three-year, $19.6 million deal with KC in the offseason.
The Texans picked him up late, but now the 29-year-old is sitting around waiting for something to emerge on what is a near-stagnant open market for cornerbacks. Don't be shocked if his career is over.