sentences:  The theory of the system is that a 3–4 structure gives the defense the greatest amount of flexibility because the linebackers are versatile players on defense, capable of rushing the quarterback, tackling runners or dropping into coverage.By mixing the roles of their linebackers from play to play, the Patriot's defense seeks to cause confusion on the part of opposing offenses.At times the Patriots will also shade their defensive linemen different ways, creating "over" or "under" defenses.