It's not so bad if you keep in mind that IB-e has a ~200mhz advantage over SB-e internally. So, that 4930K @4.5 is performs on par with a 3930K @4.7. So, the 4930K is still an upgrade unless you were able to get the 3930K to 4.8+ at reasonable voltage for 24/7 operation.
Fwiw, reliable binning has shown that only about 2% of IB-e's can reach 4.8 at 1.4v (which I would venture to guess is about the same % of SB-e's that could hit 5.0 at reasonable voltage). So it's not that yours is a poor performer, it's just that there are very VERY few exceptional ones.