Modern crooner Michael Bublé may have mastered jazz and pop, but he extends playfully beyond that across album tracks and collaborations, whether it’s classy R&B with Boyz II Men or a soul rave-up with Van Morrison. As a flexible guest star, he doubles the jauntiness of Paul Anka’s “Pennies From Heaven,” lends smooth balance to Rod Stewart’s raspy “Winter Wonderland,” and nails the torchy wistfulness of Diana Krall’s “Alone Again (Naturally).”