"Communicated" means two very different things in these two cases.
With Bulldozer, you had an AMD marketing guy saying false stuff on forums. As
you pointed out yourself in the past, the official slides for Bulldozer never said that IPC would remain constant; instead it implied otherwise, with talk of "knee-of-the-curve IPC" and talk of single-threaded performance "without significant loss" (implying there would be some minor loss).
With Zen, we've got official slides on the Financial Analyst Day touting improved IPC as a major feature of the new architecture. Of course we have to account for best-case scenarios; no one would be surprised if the actual IPC improvement in real-world applications turned out to be 35% instead of 40%. But AMD can't just issue blatant public lies to stockholders in this fashion without consequences. If Zen flops and its IPC improvements are significantly off predictions, then a lot of questions are going to be asked - and not just by the technical press, but by large investors and maybe even SEC regulators.