I've been wracking my brain around this and I'm just coming up with one conclusion about Bob.
He is a troop delivery system and that's about it.
He DOES have Ashes to Ashes and Immolation, but focus 5 makes it pretty costly to use either as you almost certainly will boost at least the attack (granted soul gathering helps offset this issue a lot)
and he has sacrifical lamb, which, if you activate in the correct order I can see making him run jacks well,
but correct me if I'm wrong, his main usefulness is just slowly tromping up field tossing down clouds of Burning Ash and popping his feat to set up nasty charge/back field strikes against the heart of your opponent.
If that IS what he really does and that is how we are supposed to use him that's fine, I was just trying to work out any other viable options.
He can be a beatstick if you have him up close once he has lost a few of his brothers.
What I'm curious about; is he effective at running jacks due to sacrificial lamb?
Is he just a walking delivery system?
I've never really understood the Silent One.