Unless you sit out free agency entirely, your draft strategy is inevitably altered by the players you sign. For Atlanta, the changes primarily have to do with the way they'll approach offense.
For most of the offseason, we assumed the Falcons would draft a receiver and add a center to improve their offense, given that those were two major trouble spots. With the huge contract given to Alex Mack and the addition of Mohamed Sanu, those two positions are addressed, and Atlanta no longer needs to sink in early round picks to take care of them. Offensively, you can argue that the Falcons really only need to prioritize guard and perhaps tight end this April, and they can focus the rest of their efforts on defense.
That's huge for Dan Quinn, who wants to infuse youth, speed, and physicality into this defense, which has needed it for such a long time. That's best accomplished through the draft, and the Falcons have set themselves up nicely to focus their April capital on that side of the ball. I'd like to think that's a sound strategy.