DD whiffed badly on Castellanos and that contract became an albatross which limited his budget options going forward. He hit with Schwarber. At least for the beginning years of the contract, he hit with Turner. Those aren't bad overall results. He had hits and misses with relievers. DD's FA signings aren't the source of the problems. His BA on those and his trades don't stand out as the problem.
The problem (which possibly is starting to change) is what it has been for a long time: the organizations inability to sign and develop hitters, particularly OFs. They have spent an ocean of bonus $, at least compared to what they spend on pitching, to sign plus amateur OF talent. I think part of the problem is scouting. A big part has been constant churn and inconsistency across levels in hitting instruction.
The Phillies have proven, once again, how extremely difficult it is to buy a championship team with the budget they have, if the farm doesn't produce. They've also proven that using the farm just to provide trade fodder to acquire veterans can't give them the long-term success they seek.
EdMuch - Yes, Miller could really help. This team needs some youthful juice in the lineup. If Crawford can be a high OBP terror on the basepaths, that will be a start. This team has too much the aura of a club of veterans drifting toward retirement. Losing the entitled Casty will help.