Pittsburg showing how to stunt. Why can't we do this?

2 sacks in last few minutes. They are rushing edge defender from outside the tackle all the way to A gap. The center has already gone to help the guard on either side and nobody blocks him. I know they run 3-4 but the way they run this stunt we could too. Send DE and DT against the OT and OG and our OLB can loop in on the A gap.