For me, it's no contest...it's Cashman.
Boone can't help that he's simply NOT very good at his job and should have never been give the job in the first place...and Cashman was instrumental in Boone getting the job...and Cashman continues to back him.
In nearly 25 years, Cashman has yet to build a championship team of his own design, and no, 2009 doesn't count either. The Boss is screaming from his grave, "GET RID OF THIS POS"
Edit; "NOT very good at his job"