One common refrain during the combine was this: Every time a player ran a slower-than-expected 40 yard dash, some wag would say "guess that rules that guy out for the Falcons!" It's an understandable sentiment, but you shouldn't get too caught up in it.
The understandable part, of course, is due to the team's own words. Dan Quinn and Thomas Dimitroff have stressed that speed is going to be a prized attribute for the Falcons this offseason, especially on defense where there are only a few players who would qualify as fleet of foot. In free agency, where players like Travis Benjamin at receiver and Bruce Irvin at linebacker are available, this makes sense, and the draft has a few speedy standouts as well.
On the other hand, though, what this team needs most of all is pure talent. They'll undoubtedly prioritize fast players across the board, but not if those guys can't play. Where you come down on the inevitability of the Falcons drafting someone like Darron Lee, then, depends entirely on whether you think he can play, because we know he can fly.
This is a long-winded way (as per usual!) of saying that you shouldn't project the team's free agency and draft plans based on who are the fastest players available. If we're lucky, the Falcons will add players who are quick and talented.