Kliff does seem too deferential to Vance.
Ultimately though this is a Keim issue. Vance is Vance and Kliff's never been a winner even in college so he's just learning on the fly. Not a knock against Kliff as I think he can get it done, but 2nd year HC Kliff wont have the command as 6th year HC Kliff.
We're not so loaded defensively for this guy NOT to see the field in a meaningful way.
To be fair, Vance has said a few times that Kliff is the HC and he is the DC. There's no HC of the defense type deal going on.
It seems to be a choice by Kliff not to be involved on that side, although granted it is hard to tell. We don't see behind closed doors and we very rarely see what's happening on the sidelines.
But as far as I'm concerned Kliff is the HC, and he's responsible for both sides.