Also, another AMD employee chimed in:
"But what's also clear is that there's a distribution of games that run well, and a distribution of games that run poorly. Call it a "bell curve" if you will. It's unfortunate that the outliers are some notable titles, but many of these game devs (e.g. Oxide, Sega, Bethesda) have already said there's significant improvement that can be gleaned. We have proven the Zen performance and IPC. Many reviewers today proved that, at 1080p in games. There is no architectural reason why the remaining titles should be performing as they are." Source: https://www.reddit.com/r/Amd/comments/5x4hxu/we_are_amd_crea...
Unfortunately you can bet Intel is going to put all the spin they can into "AMD underperforms for gaming", while the software game developers are going to slowly optimize for Zen, up to the point where this perf discrepancy will be fully fixed but people will still have the mindset that "AMD unperforms for gaming"... sigh