Of course one of the LBs is a downlineman...
But they weren't downlinemen, they ones lining up on the line were actually UP linemen, they didn't get into a 3 or 4 point stance instead remaining verticle the way linebackers usually are before a play, and gave up a solid 75 pounds against the guy on the other side of the line along with the leverage which is why downlinemen start off down.