We often talk about defensive tackles like they're all the same. In reality, they're not. We know the Falcons will have Corey Peters next year. That said, it remains to be seen how effective he will be. Then there's Jonathan Babineaux and Peria Jerry. Odds are the Falcons make Babs an offer but let him explore free agency. If Jerry returns, I'll be utterly shocked. So in short, there's a good chance the Falcons add a defensive tackle or two in the draft/free agency. I think we can all agree about that.
In practice, with their current scheme(s), the Falcons are primarily interested in 1 and 3 technique defensive tackles. This is because they operate primarily out of a 4-3 defense, employing 2 defensive ends and 2 defensive tackles. I know a lot of you already know the difference - heck, I'm sure some of you are more qualified to describe the difference. But here goes.
The 1 technique defensive tackle lines up over the inside shoulder of a guard. He is expected to draw a double team, occupying both a guard and the center. This affords the other defensive tackle a one-on-one and it frees up other members of the defense. If you have a good 1 technique defensive tackle, then you're probably pretty stout in run defense. Think of it, a defensive tackle with above-average size, clogging up the middle of the offensive front. Can't hurt, right?
More often that not, when we talk about defensive tackles, we're talking about 3 technique players. Unlike 1 technique defensive tackles, they line up on a guard's outside shoulder and are tasked with disrupting the backfield. You want them to have some bulk (i.e., at or around 300 pounds), thought not as much as a 1 technique, and they must also be nimble, quick, have happy feet, whatever.
Ultimately, the Falcons have to add versatile players. When they occasionally play with a 3 man defensive front, it'd be nice to have a 1 technique who can occupy space. Last I checked, Grady Jackson isn't in playing shape. Peters is a fantastic 3 technique, especially given what we're paying him, but his ability to contribute is up in the air. In my mind, it'd be ideal if the Falcons added one of each.