You can probably make a case for anyone in the front four, the second level, or the backend.
If everyone plays their individual roles well, it is the collective whole that is the fine tuned machine.
The sum will always be greater than the individual parts.
But it also requires a coach/coordinator that is able to utilize the talents of the individuals to create schemes to put the offense at a disadvantage.
For me, always have been Sherman, is not the same leadership when he is at the field, since he left the defense is not the same even with Bobby Wagner, he gives security and when there is problems he talks with the team.