After building a grassroots following and serving as a gateway drug to the jam band scene for many college kids, O.A.R. finally shed the "next Dave Matthews Band" label by toning down its island idiosyncrasies in favor of polished, radio-ready singles. Their upbeat lyricism and soaring refrains, however, make them virtually indistinguishable from scores of pop rockers. But the veteran Maryland-based crew seems to be diversifying again. This time, oddly, it's with hip-hop; the quintet recently collaborated with B.o.B. on the ultra-slick Olympics anthem "Champion" while Russell Simmons and DJ Logic appeared on last year's King. The awkward results aren't really helping their cause. The simplistic, second-rate reggae of Rebelution fills the opening slot. Tickets are $25–$39.50 for the 6:30 p.m. concert. —Spencer Griffith