In the late 1940's and 1950's cool jazz evolved directly from bop. Essentially it was a mixture of bop with certain aspects of swing that had been overlooked or temporarily discarded. Dissonances were smoothed out, tones were softened, arrangements became important again and the rhythm section's accents were less jarring. Because some of the key pacesetters of the style (many of whom were studio musicians) were centered in Los Angeles, it was nicknamed "West Coast Jazz." Some of the recordings were experimental in nature (hinting at classical music) while some overarranged sessions were bland but in general this was a viable and popular style. By the late 1950's hard bop from the East Coast had succeeded cool jazz although many of the style's top players had long and productive careers.