Wondering that myself.
Personally, I like this. If your starters aren't performing, sit 'em. Get those young guys in there and let them knock opponents around, give them a shot to show what they can really do.
Ruud has been the only senior LB making plays consistently. I am very happy to see Brandenburg and Dillard getting promoted. He's the future of the LB corps.
As far as Bowman being listed at 2, maybe he's just more banged up than we know right now. Certainly not a stretch given his history.
Another thought:
If one of the DTs isn't at 100% percent, and faced with Okie St.'s offense, maybe we could be seeing some 3-4 w/ Octo, Bb, Dillard, and Ruud?