Only one position on offense has a senior starter right now (Noa -or- Williams, both seniors). Out of 29 spots on the offensive depth chart for this week, only 4 are seniors, and 7 juniors. In other words, almost 2/3 of the guys on the offensive depth chart are underclassmen.
I mentioned this elsewhere, but those three seniors anchoring the lines last year were originally Bo's recruits. Now we have zero seniors on the OL depth chart, and a handful of junior Riley recruits, ie guys who were mainly recruited just for pass blocking.