At same TDP Zen would be 21% faster than the 5820K, since it has 33% cores advantage this amount to 9% disadvantage/core for Zen.Assuming this is compared to an FX-8150 (CB R15 ~550), the score for Zen is roughly 1100. This is comparable to an Haswell-E based sixcore i7-5820K. But considering Zen has a 2 core advantage it would possibly mean that there is still quite a big gap in Singlethread performance to Intel.
Of course that s without accounting for the eventual MT scaling penalty of CB from 6 cores to 8 cores, wich should be quite low, though, dunno how CB scale at this level.
Also that s assuming that SMT scaling is comparable to HyperThreading.
Anyway ST wise any hope that there will be a big gap is a pipe dream, besides we dont know the frequencies, what if it is at much lower one than HW..?.