Just to add twopenneth - the weighted average favours those that are performing well and marginalises those that are performing badly over a long run average. It is not likely to respond materially with an outlier prediction unless that outlier comes from one of those performing well. I'm trying to say it self polices Pat and there isn't a need to be concerned about it. With the Mean, your assertion is certainly true but for the Weighted Average, the existence of an outlier as spoiler is very, very limited.
On another note, I have observed that Pete does v.well during bearish markets (as he is a perma-bear) and it is no surprise to me that Viel has done well as he is a perma-bull and conditions right now are bullish.
Over the weekend, I might take the 2012 results to see where in the bull/bear spectrum regular participants are in their predictions vs actual. Then I'll draw it up as a distribution which will be quite 'blocky' but probably quite entertaining to see.