Why is this so intriguing? Because Langford is not a 4-3 defensive end. He's a 3-4 defensive end who played under Mike Nolan in Miami, and he's not what you would call an elite pass rusher. In four seasons with the Dolphins, the 26-year-old has 7.5. Mario Williams, he is not, but he does manage to generate pressure nonetheless.
The likeliest role for Langford in Atlanta would be a hybrid defensive tackle/defensive end who primarily played at DT, assuming the Falcons make good on their promise to keep a 4-3 defense in 2012. He's a gifted run-stopper and a player who was moderately useful in 2011 and very good in 2010, and he's one hell of a sure tackler at minimum.
So why the interest? You have to assume Nolan's familiarity with him has something to do with it, but I doubt that's the sole reason. Jon Babineaux has looked a little slower and a little more banged up in recent years, and while Corey Peters has been uniformly excellent over his first two seasons, the Falcons don't actually have a ton of terrific players in the middle. Peria Jerry has shown flashes of brilliance but has struggled to get real playing time, and Vance Walker is a perfectly solid backup tackle. Unless Jerry miraculously turns it on, Peters is just about it for upside.
Langford would be, at minimum, a part-time starter and a valuable rotational guy who would bolster the depth inside and outside. If he comes for a reasonable price, he would add a little to the pass rush, a lot to the run-stopping capabilities of the front four and that prized versatility the Falcons love so much.
I could see it happening. Can you?