When was the last time our DTs used a swim move?
They schematically don't go into the backfield. They "control" the line of scrimmage. They aren't supposed to be using swim moves. Understand what the coaches are having the players do and you will understand why the defensive tackles don't make plays. This is the reason Chickillo is slammed by the fans and praised by the coaches. He is doing what he is coached to do. His Dad was an all-american DT. Do you really think he doesn't know technique? He showed it in high school. SCHEMATICALLY, you are expecting him to play like a 4-3 end or 4-3 DT where he can get into the backfield and be disruptive. He is not playing that position. His role is to 2-gap the offensive tackle to stop the run. Then, he sheds to make the tackle. It is as misdirected as asking why Peyton Manning doesn't run like Vick. They are playing different positions even though the name is the same.
Watch a game from youtube with this in mind and it will become very clear.