Dr. John Mack is a serious, careful and courageous research. Consider. If you were a Harvard Medical School professor with a Pulitzer prize and a sterling reputation would you endanger it for the sensationalism of "alien" abduction? Even if you were confronted with evidence of strange events, why put up with all the headaches? That Mack did proves him to be a true man of science, one who investigates phenomena instead of prejudging it as valid or not valid.
Mack is not saying outright that alien abductions are "real." He is saying that something is happening that leaves a real and lasting effect on people. These events have certain characteristics in common. Mack is mapping the terrain features of a new psychological continent using the case histories of individuals who have come forward. These individuals are also taking serious risks.
In truth the issue is not alien abduction per se, but what Mack calls the politics of ontology.
Personally I have had more than my share of "interesting" events. Mack's book, though not overtly written for this purpose, is a guide by which those who quietly keep to themselves may evaluate how their experience compares with others.
If you are interested in a serious exploration of this topic, this is the best book on the subject.