As the lead singer for Matchbox Twenty, Rob Thomas was at the forefront of the polished mainstream alt-rock that emerged in the late '90s. Unlike the grungy Seattleites who defined the first half of the decade, Thomas was clean-cut and not opposed to classicist pop hooks or sophisticated production gloss, a combination that worked to soften the palpable angst at the heart of Matchbox Twenty's 1996 debut, Yourself or Someone Like You. The band's first record built into a blockbuster, by which time Thomas stepped outside of the confines of the group to co-write and sing "Smooth,...