I think it's been neat from an architecture perspective for AMD. TSMC (and AMD) has had trouble matching the frequencies that Intel has been attaining on their 14 nm node, so the only way they were going to beat Intel's single threaded performance was to increase IPC enough over Intel that the frequency gap didn't matter. Seems like they finally got there (the point where their IPC is high enough that a 4 point something GHz Zen part can exceed the single threaded performance of a 5 point something GHz Intel part).