In switching to the 43, the Patriots open up a ton of potential for their defense.
They have the option to two gap. Before I get in too deep here, let's think about what their starting 43 will look like. Burgess, Warren, Wilfork, Green. This is backed by (Will to Sam) Guyton, Mayo, Thomas. Look at that on paper and think about it. That would be regarded as one of the best front 7's in the entire NFL. Nevermind two of the best two gappers in the league flanked by highly capable ends. The tandem of Warren and Wilfork is vastly superior to Henderson and Stroud, who were regarded as the best interior tandem in the NFL not too long ago. While they two gap, it will enable the linebackers (remember: all of which are sub 4.6 guys)to pursue and get after the football freely and unobstructed. Our linebackers in the 43 set are flat out the best in the league on paper.
They also have the option of one gapping. In the one gap scheme, they shift Wilfork to the three tech, allow him to get after it, and attack the LOS with a myriad of looks. This will enable their best defender to become their focal point, and will clearly create unmitigated chaos behind the LOS. While I am as staunch a proponent of the 34 as there will ever be, this team in the 43 will revert to 03 defensive form. I never thought that I would say this, but I'm dying to see the 43.