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As a scientist, I still find the 'shaft' portion of the hockey stick much more egregious than the grafting of 'the blade' onto the end. The fundamental assumptions of reconstructing long-term temperature trends from tree rings assume that the trees are primarily temperature stressed. This is the only time where tree rings depict -temperature-, as opposed to just precipitation or nutrients. This is absolutely not 'random trees', but trees picked to be right at the edge. And the trick is narrowing it down to just a very few trees as representative. This should all work fine for weather. But climate as about -changes- in long term patterns. You can hear this from practically every participant in the 'humans caused it you filthy denier' side. More droughts, more hurricanes here, more floods over here, warmer Arctic, colder -near- the Arctic, more tornados.... All portrayed or predicted as not just weather shifts, but longer term, continuing and deepening trends. Every single one of those changes is a change that can shift the treeline itself. And that, in turn, means that the choices of -which- trees changes with time itself. This is -exactly- the 'hide the decline' problem exposed by Mann's -own- graduate student Dr. Abadneh. The -same- tree areas re-examined in a later period are no longer 'temperature sensitive'. They go -down-, instead of up with the rise from 1960 to 1998. Fundamentally, this means you can use Mann's vaunted method to determine decent tree proxies for the period in which you already have surface station temperatures to compare them to. But when you extrapolate (always a special problem!) to pre-instrumental periods, you're going to end up with random results. Because "the" trees don't work across climactic shifts. It's really no wonder that Mann's methods produce a near-identical hockey stick when the entire dataset is shoved in upside-down and backwards. Because the key piece is finding the best 'current' proxy ... and then assuming there's sanity in extrapolating wildly into history.