You could swing a stick and hit a dozen prognosticators gassing about the future of marketing, advertising and the much humbler brethren in public relations. The swirl created by Google’s and Facebook’s omnivorous ad engines has sent the traditional ad agencies into a frenzy. What’s more, technology platforms promising hyper-targeting and precision measurement have opened the door to an AllBirds-wearing army of management consultants. Suffice to say upheaval abounds, so I was eager to see veteran storyteller Ken Auletta of the New Yorker make sense of it all in Frenemies, an easy-to-read account of the existential battle between the “Mad Men” creatives who find themselves under siege by marketing data analysts.