How well can we measure performance?

Imagine Cass Sunstein and Richard Thaler writing a co-authored book review for The New Republic. The book is Michael Lewis's Moneyball, which pretends to be about baseball but is in fact a profound meditation on behavioral economics, management science, and how hard it is to measure value. An obvious question: if it is so hard to measure the performance of first basemen, when there is a slew of publicly available statistics, how about the rest of the economy?

Thanks to Will Baude for the pointer.