Farrell tactically was fine. He was not great, but he was not terrible. (like Matt Williams terrible) Tactically he did a pretty good job in the ALDS. (no way to tactically work around 2 horrific starts ... his moves were crucial to winning Game 3, and he did everything right in Game 4)
He got respect - and after the Bobby V experience, having a normal human being in that position was a tremendous plus.
However, he did not seem to be very good with working with a younger team. He was good in that he played kids - which not all managers do. But - and a lot of the reporting surrounding the firing noted this - the kids the Sox had were all smart, high character guys. But they often were also guys who were very hard on themselves - and Farrell was not the sort of guy who can tell the kids to take it easy or just helping them relax.
Can Cora be able to work with a lighter touch - I am excited to find out.