The reality is no one is 100% to blame. Every team is combination of current GM, directors, president of operations (whoever) and past executives. Luck is also involved.
This past years woes were combination of some bad moves made by Dave at the end of his tenure, a few bone head moves by Bloom, and horrible luck on the injury front.
Regardless, it’s 100% on them now. After this offseason, the 2023 Red Sox are going to be much more Blooms team than last years, and significantly more than the year he took over.