benlessard, on 2013-September-30, 22:08, said:
I don't think either of these conclusions follows. Certainly we are not as good on opening lead as double dummy. However, humans never play as well as double dummy; even a computer with unlimited processing power won't play as well as double dummy because of incomplete information. Arguably the opening lead is the toughest part of the game because we have least information (can't see dummy, no signal from partner yet, etc).
The fact that overall human results are close to double dummy (especially at the slam level) is interesting but not really indicative. There are hands where declarer is likely to do worse than double dummy (for example, where the only way to make is some anti-percentage play like dropping a stiff king in an eight-card fit). There are other hands where the defense is likely to do worse than double dummy. All the overall human results suggest is that these hands are close to equally common... not what will happen on any particular hand.
With that said, I think there is room for improvement on opening leads, and the findings of this book are certainly interesting. It's well-known though that both ace leads and passive leads fare better double dummy than single dummy. The main reason is two assumptions: that giving declarer a guess he could make himself will never cost a trick (true double dummy, but not single dummy) and that the defense will never err after the opening lead (again true double dummy, but not necessarily single dummy).