I don't know what you're looking at, but this should say it all.
First, an i5 2500K vs. a FX 8150: http://www.anandtech.com/bench/Product/434?vs=288
The 2500K wins all but the most highly threaded benches.
Second, an i7 3770K vs. a 8150: http://www.anandtech.com/bench/Product/434?vs=551
Except for the Civ V anomaly, the 3770K destroys the 8150.
The reason is that Sandy Bridge and Ivy Bridge are much faster and more efficient architectures than Bulldozer and much faster than the architecture of the Phenom II and Athlon II, as well.
Basically, you get what you pay for. AMD offers decent performance at a decent price, while Intel offers excellent performance at a premium price.
AMD covers the budget market and Intel covers the enthusiast market.