Except that we don’t in fact want silence from a musical, and “Redwood” would make a dreary play. Happily, whenever its book drifts into familiar tropes of the genre, the songs pull it back to its wild and unsettled heart. Diaz’s rangy, propulsive music has immediate curb appeal but with a scary, questing quality that provides the necessary big endings without pat resolutions — a combination that hits Menzel’s sweet spot over and over. The other characters also get strong defining numbers, all beautifully sung.