Not having a ton of power is okay, if you know how to hit everywhere else in the field. The problem is outside of home runs, the Sox hitters just aren't that good. Why they aren't that good is a whole different topic that could take about 60 pages to write up on.
My opinion on Walker, when he was fired, was that he wasn't the problem, but he sure as hell wasn't the solution. I feel the same way with Manto, I thought it was a lazy hire when it was made, and I agree that this points to bigger problems in the organization.