On Goodbye Lullaby, Avril Lavigne once again attempts to leave behind the mall-punk persona that made her one of the biggest pop stars of the early ’00s. But Lullaby finds Lavigne caught in an awkward transition between her bubblegum past and an ill-defined “adult” sound. Lullaby moves tentatively toward MOR pop on overproduced, mid-tempo songs that abandon the compulsively listenable pop-punk that remains Lavigne’s most inviting calling card. The shimmering acoustic-guitar strums, tinkling piano licks, and goopy strings on limp tracks like “Darlin’” and “I Love You” lack the infectious hooks of her best singles as they plod along with little energy. At least Lavigne exhibits some of the old spunk on “Smile,” dropping a litany of curse words and asserting her right to be “a crazy bitch” who does “what I want when I feel like it.” But Lullaby truly springs to life when Lavigne drops the pretense of being some kind of newfangled Lilith Fair songstress and goes back to producing bouncy head-bobbers on the catchy, bratty single “What The Hell.” Lavigne is a divorced singer-songwriter about to enter her late 20s, but on Lullaby, she would’ve been better off not acting her age.