Looked at the Cinebench R15 chart AMD provided in their PDF.
From the notes you can see that they used FX-7500 (Kaveri), FX-8800P (Carrizo) and FX-9800P ("Bristol Ridge") in the comparison. FX-7500 scores 179 in R15 MT (pclab.pl) while FX-8800P scores 234 (my result). For that part the chart is absolutely correct (Kaveri = 100%, Carrizo = 130%, "Bristol Ridge" = 150%). However between Carrizo and "Bristol Ridge" the things get interesting. According to the chart "Bristol Ridge" should score 15.4% higher than Carrizo, i.e 270 points in Cinebench R15 MT test. The chip would need to run ~3200MHz in order to score 270 points...
FX-9800P has the same TDP as FX-8800P 15W / 25W (base boost), however it doesn't support cTDP > TDP configuration. Since Cinebench R15 takes less 200 seconds to complete in MT mode, both of the chips will have the 25W STAPM limit available throughout the test. With 25W power budget Carrizo is able to sustain <2700MHz frequency in Cinebench R15. FX-9800P has higher base and boost frequencies than FX-8800P, however the maximum frequencies doesn't matter when the effective frequency is limited by the power budget. So where does Bristol Ridge find the additional power worth of 500MHz, since the silicon itself is identical? FX-9800P also runs at higher voltages than FX-8800P does.
"50% performance-per-watt generational uplift" would also suggest that AMD claims that Bristol Ridge (7th generation) has 50% higher performance per watt than Carrizo (6th generation), which sounds pretty bold to me. Should be pretty hard to achieve, unless Carrizo has some serious errata which is yet to reveal itself...