They triangulate country bounce, classic-rock flex and jam-band wiggle like crossover wizards. Their frontman has a buttery midrange tenor, can sell the heck out of a song, and keeps his lumberjack beard nicely trimmed. With the possible exception of their relentless likability, there’s nothing unlikable about theZac Brown Band. On their fourth LP, they bang out styles with such preposterous ease — Seventies Philly soul, old-timey gospel, Celtic folk, metal, reggae, jazz — they could incorporate as a single-band music-placement agency.

If only they reached a little further. “Beautiful Drug” works pharmacology-of-love metaphors into an arena-pop framework with a side of banjo. Guest Chris Cornell adds hard-rock cred to “Heavy Is the Head,” which nods to “Smoke on the Water” and misquotes Shakespeare. “Castaway” is Jimmy Buffett-ish life-is-a-beach redux, “Homegrown” a boilerplate small-town-pride anthem. The sole head-turner is the sole cover: Jason Isbell’s “Dress Blues,” which fills the military-tribute slot common to country LPs with uncommon depth. Brown magnifies it brilliantly (even if he swaps the phrase “God-awful war” for Isbell’s “Hollywood war,” the song’s linchpin). A pop star who can deliver like this should deliver more.