For Zen, they don't have to be the best, just good enough. Frankly, for consumer Intel has been good enough since the 2600 days (except on the mobile front). So Zen should be fine in that market.
Good enough or, "we're #2!" might be all that's needed to chip off some server shares. Which is good for AMD. But for my machine I'm not sure I'd give up any single threaded performance for the promise of 8 physical cores with SandyBridge level IPC.