What accounts for this five-song EP's splash on the pop charts? Can't be the lyrics, which are unremarkable in their I-hate-cops, you-can't-mess-with-us swagger. Nor is it the production, which confidently thumps and bubbles but doesn't do much else. What sets these Cleveland rappers apart is a vocal style that deftly weds a brisk hardcore delivery with melodic, almost jazz-like complexity. B

