It looks like the author is a glass-half-empty kinda guy. The sentence immediately preceding that justifying the conclusion that something "went wrong" is: > T

It looks like the author is a glass-half-empty kinda guy. The sentence immediately preceding that justifying the conclusion that something "went wrong" is: > The results of the case studies indicate that the pre-release defect density of the four products decreased between 40% and 90% relative to similar projects that did not use the TDD practice. Sounds like a net win to me - possibly 35% more effort, for a possibly 90% "better" product. 90%relativetosimilarprojectsthatdidnotusetheTDDpractice"