Well, the Oilers didn't gut their roster to get a a star dman, but they certainly traded away their best chip to acquire a 2nd pairing shutdown guy, with little speed and zero offensive instincts. In any reasonable world, Taylor Hall gets moved for a true #1 dman, even if you have to add. Their 2nd best trading chip was moved (to acquire a useful piece plus save salary from what we're told) for a former 1st round bust that is now our checking centre. A first and 2nd rounder were moved for a slow skating defenceman who is not even in the league anymore, and for whom we lost in an expansion dispersal draft anyhow.
I'm not so much against the actual trades, but what we got back for them.
The deepest roster down the middle that you speak of, boasts the league best player, another who can't seem to drive his own line despite eating up an enormous chunk of valuable salary cap room, and provides points while playing with said best player (which would make him a winger in a lot of occasions), a 3rd line centre that is good at killing penalties, but not a whole lot else, and another centre who is in his 2nd full year and has a lot to prove.
So, while the team may not have been gutted to acquire pieces, it sure left some serious holes all over it, while providing serious cap issues going forward.
Do we have a lot of depth? I don't know about that, most prospects are too far down the road to know at this point. There are very few of them, if any, that are can't miss. A whole lot of question marks, in my mind.