Another fairly famous pass rusher has hit the open market. Today it's Charles Johnson , once a Georgia Bulldog and long a productive Carolina Panther. On Monday it was Mario Williams , the man drafted ahead of Reggie Bush in 2006.

Given that the Atlanta Falcons haven't had a decent pass rush since Claude Humphrey -- OK, I exaggerate; John Abraham was great when the mood struck, and Chuck Smith made the biggest defensive swoop in franchise history -- we around here get all abuzz at such developments. Should the Birds sign Johnson? Sign Williams? Sign both?

And here's where I say, not for the first time: NFL free agency is, in the main, wildly overblown.

A few recent local examples: Tyson Jackson, Paul Soliai, Jon Asamoah, Brooks Reed, Justin Durant, Steven Jackson, Ray Edwards. None made a smidgen of a difference. Now, Michael Turner -- he was a free agent who made a difference. But he's the exception who proves the rule.

Granted, a few franchises have been changed by free agents: Reggie White to the Packers, Drew Brees to the Saints, Peyton Manning to the Broncos, Kurt Warner to the Cardinals. You'll note that three of the above are quarterbacks, and few first-rate NFL quarterbacks are allowed to become free agents.

Much of this has to do with cold reality: Pro football players don't last as long as they did. The NFL Players Association has claimed the average length of a career is 3.3 years . Just this week, the Wall Street Journal -- using data from Pro Football Reference -- maintained the average career now spans 2.66 seasons , having dipped from 4.99 seasons in 2008.

Williams is 31. He had 38 sacks from 2012 through 2014. He had five last season. (He contends it's because Rex Ryan's defense didn't emphasize his talents.) Johnson turns 30 this summer. He had 62.5 sacks from 2008 through 2014. He had one last season. (He played only nine games due to injury.)

Baseball clubs have become more cognizant that free agents shouldn't be paid on what they've done but what they're apt to due after they sign the new contract. (Then, being baseball clubs, some of them turn around and shell out nine-figure deals.) The same should apply doubly if not trebly to the NFL, where players get hurt more often and burn out more quickly and not many non-quarterbacks are viewed as truly indispensable.

Were I the Falcons, I'd be leery of signing any free agent who's 30 or thereabouts. Bruce Irvin, lately of Seattle, might not be worth the $9.5 million per year John Clayton of ESPN suggests he'll command , but he does have this going for him: He's 28. At his peak, Irvin hasn't been the player either Williams or Johnson was. Irvin has 22 career sacks. (He's also a linebacker; the other two are hand-in-the-dirt D-ends.)

And yet: Irvin's NFL career began in 2012. Williams has been a pro since 2006, Johnson since 2007. I don't know that Irvin would be a difference-maker, either, especially at that price. I do think he'd be a sounder investment than Williams or Johnson.

Further Falcons reading:

Cutting Roddy White was the right move.

Shoves at the combine: The Falcons are at it again.

Yikes. The Falcons' 2016 schedule is the NFL's toughest.

The Falcons cut Durant after one year, and I say, "Hmmm."

A defensive coach to offense? The Falcons again stump the band.

Value bet to win the next Super Bowl? ESPN's Tuley says the Falcons.

The Falcons retain Dimitroff, so I guess it's still all Smitty's fault.