...have a capable backup to step up and fill his shoes so coaches are moving Deilman from tackle to center and then shifting a lot of others around to backfill.
Dielman has never played center before so it's an unknown if he'll be able to pick it up or how many games it'll take to learn it. Bolles is a JC transfer and those guys are always crap shoots if they can transition to the D-1 game.
I think Williams at qb is a total unknown, the RB that backed up Booker last year is serviceable but everyone behind him is unproven. TE is solid but WR is totally unproven. 75% of your offensive production from last season is gone and in nearly every case you have an inexperienced player(s) replacing them.
All that inexperience will lead to mistakes, turnovers and poor execution which Will impact the defense by keeping them on the field a lot or making them defend short fields.
It's a little unreasonable to have to replace 75% of your offense but expect it to be the same as last year when last year was your best offensive showing in the entire time you've been in the pac12 when you had a 4 yr starting QB leading your offense