As far as in game decisions go, managers do not have as big an effect as most people think they do. I've always felt that the most important aspect of a manager's job is the management of the players and the clubhouse. IMO, the team's record fall mostly on the players, not Farrell and not Dombrowski.
Having said that, when a team underperforms like this one has, and I'm thinking mostly about the sloppy defense, it's fair to question what's going on with the coaching staff.