Teams are spreading us out more.
It helps neutralize a 4 man front's rush. That and a running QB which they also have.
That's why a lot of teams play spread teams with 3-3-5 stack or 4-2-5 and send people from different angles to confuse blocking schemes.
Its hard to pressure a spread like NDs especially with the way the get the ball out fast and keep you honest with the read option.
Diaz did a pretty good job against it the offense has to help by keeping the defense off of the field and scoring and trying to force them out of the spread, dink and dunk, read option gameplan and force them to throw more downfield. That is what allows out 4 man front to start getting hits on the QB.