In their two other games - against TOLEDO and KANSAS:
The Illini defense surrendered:
957 yards
54 first downs (yes, 54)
62 points
16 of 28 on 3rd down
And an average of 35 minutes of possession for the opponents
Illinois has a couple good defensive players (#4 is outstanding), but they have a horrible defense.
Thankfully, for them, they now get to play a bunch of Big Ten west teams that have worse-than-horrible offenses (which also propped them up last year). A schedule of Minnesota, Nebraska, Wisconsin, Purdue, Northwestern, Iowa, Indiana, FAU, and Maryland will make a "just bad" defense look like the 1985 Bears.
Rutgers likely has a better defense than Illinois - but they don't get to play in the west.