Dave McCullough wrote about John Farrell at the .com and explained quite well why people should perhaps relax a bit when thinking about in-game decisions about managers.
Ultimately, it is the management of people – the egos, the foibles, the day-to-day grind of twenty-five (to fifty) men getting paid huge amounts of money – and the management of the media responsibilities – the press conferences, the sit-down interviews with team broadcasters and PR, the fulfillment of team marketing initiatives (buy a brick!) – that determines whether or not a manager is “good” at his job.