Crennel, who sat out the 2009 season after being fired by the Cleveland Browns following a 24-40 stint as their coach, comes to Kansas City with an excellent reputation as a defensive coordinator after serving as Bill Belichick’s right-hand man in New England.
Known for using a clever blend of coverage and pressures, Crennel’s system is deeply rooted in a “quarter-quarter-half” cover scheme that has the ability to suffocate offenses if executed properly.
The field is split into quarters with the strong corner (typically the left corner because most offenses tilt right) and the strong safety each responsible for covering a quarter of the field. On the weak-side, the boundary corner and free safety play a half-field coverage to create a double team on the split end (X-receiver). With the corner playing a “cloud” technique (corner is aligned three-to-five yards off the receiver forcing an inside release on all routes to ensure that the safety is able to stay on top of the receiver down the field) to disrupt the release of the receiver, the scheme can make it difficult for the quarterback to find open receivers.
Check out this great article that explains a little bit about Crennel’s defensive scheme. Very good read.