The pianist has toned down the antics that once made his performances unwatchable. But, sensitive musician that he can be, he still finds musical structure elusive. His Chopin Piano Concerto No. 2 on Saturday vacillated between fast and flashy and slow and self-regarding. While ravishing to the ear, his languorous way with the slow movement came close to impeding the music's natural flow.I'm almost thinking it's time to give listening to him another go.