It doesn't matter if it's clocked faster, they are two completely different architectures. Bulldozer was specifically made to clock faster; the original engineers deliberately forwent single-threaded performance in favor of multi-threaded performance (hence the octocore jazz) for parallelization. Either way, it goes without saying that an i5 at its theoretical max stable OC would be much faster than a Piledriver chip at its max OC.
There's nothing to suggest that SR will be 20~25%+ faster than Piledriver, btw. All there ever was, was just that "30% Ops Per Cycle improvement" from that slide from Hot Chips 2012, and even that was most likely in comparison to Bulldozer, not Piledriver. This would put SR about 15% faster than PD, which goes in hand with this:
Of course Kaveri was pushed back from its original projected release (early 2013) so who knows what potential improvements they could've made since then.