Brez has certainly shifted the focus to pitching, and he's made dozens and dozens of moves to add or swap out pitchers. He was bound to get some wrong, but as of now, it seems he was wrong on way too many, especially the ones he paid the most for, except Crochet & Chapman, maybe.
Some moves like Sale and Priester (traded and not the traded for deal) looked real bad, at first, but might be hard to judge at the time of the trade (Sale) or in hindsight (Priester.)
I think if blame must be assigned, and in this culture, it is unavoidable, it seems JH, Brez, Cora and others all share in the blame.
JH's cut in spending set us so far back, that recent spending upticks seem like a drop in the bucket.
Brez has not spent much of that uptick spending wisely. He's made some good and some bad deals, but has built up the farm pitching outlook, which is speculative value and not actual value, yet.
Cora has let his favoritism/loyalty cloud his judgement and actions.
DD left us with some serious budget issues and a pretty lowly ranked farm, although the prospects he did not trade turned out to be better than the higher ranked ones he traded away to give us those 3 very nice seasons. Bloom did some good building back up the roster depth but failed at adding the right mix of star power with the too few chances he did get to spend more (Story & Yoshida.)
Add this all up and we get the perfect storm of futility.