Bulldozer was partly a big gamble and partly a big mistake by the engineers. They bet that software programmers would be more than happy to take advantage of a processor with two integer cores instead of using SMT. Sadly, as Intel dominated the market by a large percentage, they didn't optimize anything for it. They also bet that having 8 independent integer cores would be the best way to go instead of tying the pairs together. This resulted in a deficit since the pairs shared a single floating point processor, and when they couldn't take advantage of both integer threads.