Over at the New Yorker, Jill Lepore calls out Clayton Christensen on his innovation and disruption theories:

In his original research, Christensen established the cutoff for measuring a company’s success or failure as 1989 and explained that ” ‘successful firms’ were arbitrarily defined as those which achieved more than fifty million dollars in revenues in constant 1987 dollars in any single year between 1977 and 1989–even if they subsequently withdrew from the market.” Much of the theory of disruptive innovation rests on this arbitrary definition of success.
I love Christensen’s work, but it’s always interesting to read opposing views.