This is a very good manual for learning about the Split 4-4 (I know . . . another shameless plug for JrTitan and his hard work). This a defense that has as many variations as any out there. It seems that everyone has their own "tweaks" for how to play it. JrTitans' version is excellent at describing what to do and where to align. it is user friendly and allows a coach/coaching staff to quickly install the basics of an extremely sound defense.
In the past (we are talking approximately 40 years here) we have put our DEs head up the TE and had our OLBs aligned 4x4 or 3x3 off the last man on the line of scrimmage (more of a 4-2-5 look). Our inside 4 (DTs and ILBs) were either in a split, a strong shade, or head up and stacked.
This year, we are going to put our OLB to the TE side head up/inside shade of the TE (depending upon the TEs skills) and move our DE wider for a more aggressive contain. One thing we will need to find is more aggressive DT play - players who will force the offense to double team them. This past year (because of injuries and partly because of a new scheme) we were playing inexperienced and physically smaller kids inside and that hurt our ILB play. Two seasons ago (different school) our DTs gave us tremendous effort which allowed our ILBs to be more aggressive.
The defense is extremely flexible and allows for multiple blitzing (much like a 3-5/3-3 stack front) without having to give up too much in terms of pursuit. IMO, it is one of the most flexible looks - both fronts and secondary - for the defense to employ.
