Dockett is a good example of a good player can play in any scheme. No way he was drafted to be a 3-4 DE but he has still adapted and played well. He would be an absolute beast if he played the position he was drafted to play, 4-3 under tackle. Heck, he's still a beast but his production is limited by the poistion he's playing.
He is a beast in penetration and absolutely horrible two gapper. He has not adapted to anything and not played well when asked to two gap. He just can't do that at all, i watched the D-line every single play every year,multiple times, he just can't shed and laterally dominate in the run game.
All he does is (and all he can do) is making that great initial speed step into a gap shaded onto a lineman.
Every time he was taken straight on in a 0, 2 or 4 technique and aksed to powerstep instead of making the speed step, he was horrible, not even average, the tapes don't lie, he just can't do that. He is also horrible in reading plays and reading plays is exactly what you need when you are in 2 or 4. reading plays is exactly what is the strength of the Steelers D-line.
he is a disruptive beast and you assign him to one gap,3 tech, because that is what he does well, and that is the only thing he does. He would be fantastic in Tampa -2 scheme, would have more sacks clearly.
Horton only knows a defense where all three lineman can stop the run in two dimensions. Our defense has lineman that can stop the run in one gap. It's a huge difference and completely different style of football. It's much more important than 3-4 or 4-3. Much bigger difference is whether you play one gap or two gap, that is defining a philosophy much more. It's about assignments.