It’s not the front office. They developed an excellent starting pitching staff, and a pretty good bullpen for being all cheap contracts.
The problem is there simply isn’t enough beans to pay a bunch of expensive hitters to go with their pitching and they had some bad luck.
That Hiura and a Corey Ray turned out to be busts as Top 10 picks hurts them. Jackie Bradley Jr. being a bust hurts them (cash, deferred cash, prospects, and two years later they have a middle reliever and a AAAA starter to show for it). Mitchell and Frelick suffering significant injuries hurts them.
With not much cash to spend, and no blue chippers knocking at the door of the majors, the front office did the best they could getting middling band aids who might have some upside (Tellez, Urias, Anderson, Winker, etc.) and hope to get lucky. Their roll of the dice just didn’t pan out.
Now there’s really no way get better at this point absent extended hot streaks for those aforementioned players, or breaking up the team and trying a new mix of players