The difficult thing is that a lot of the evidence has come about since the publication of the Hockey Stick. I believe the New Zealand ice core that confirmed the Little Ice Age was some time after '98 (I could be remembering completely incorrectly). The problem is not so much that Mann came up with his Hockey Stick (although I have read a bit about the M&M study and something to do with Mann improperly copying convenient data from one series into another), but that he and his supporters clinging to it in light of evidence confirming the MWP, LIA and the M&M and S&B studies.