The Back Four
The one place Phillips has always had immense flexibility is in the back four. He has tended to play with an in the box safety and do a combination of cover one and cover three, but for him the front seven allows a defense to do whatever it wants in the back end. For the Raiders, they are in a position to play more like the Packers than the Broncos
Last season when the Raiders beat the Broncos, they did it playing primarily with two deep safeties. The addition of Reggie Nelson does not change this outlook. Nelson is a zone based free safety that has played almost exclusively in zone his entire career, especially in Cincinnati. Last season the Bengals played primarily single high safety over 70% of the time, but in seasons past with Mike Zimmer, he played in a two high safety system.
What the Raiders lack is a true strong safety. Someone who can play in the box, cover a tight end man to man, and play in short zone. What the Raiders do have are two deep ball hawking safeties in Nelson and Allen. Before Allen was injured last season, he had a preseason game where he intercepted two passes playing the hashmarks.
Combine this with the fact the Raiders have when Aldon is on the field, four inside linebackers who are all atheltic enough to cover tight ends along with a solid front five that can get after the quarterback, and you have the ideal situation to play two high safety concepts.
We cannot forget the cornerbacks either. Both Smith and Amerson do well in man coverage, and whether it is quarters coverage or two shell coverage, both allow them to play the boundaries or in press bail where they are trailing the receiver in a position to make a play. Against the boundaries, press bail is key because being short of the receiver actually makes the receiving window smaller. What Smith and Amerson do well, is use the boundary as an additional defender to shrink the throwing space.