In every fanbase there are a % of people who like to blame managers, specific positions, coaches, some combination... what have you. There's been a fire <manager> thread for every single manager the Nats have had. I've never seen it as anything more than heat-of-the-moment venting, much like the gameday threads. Consider it therapy for the poster(s), whether you think they actually believe it or not.
I get some people don't like to be around negativity, but I honestly can't bring myself to believe that WNFF is particularly exceptional in terms of negative or positive attitudes compared to the average generic sports website. We've got a collection of posters who cover the range of attitudes and emotions, some more consistently than others. I've learned not to take anything on the internet too seriously.