It is however clear that they were not the best statisticians, and if you're doing complex statistical work (which of course, global temperature measurements are), you need to have at least on statistician on your team otherwise your work is going to be inaccurate. That is what happened with this group of scientists, as the investigation found.
This is perhaps best exhibited in the "hide the decline" controversy (good overview here). Because of poor statistics they never dealt with the divergence problem. In other words, if tree rings don't accurately match modern thermometer readings, how can we expect to rely on them for historical temperature measurements?