Russia’s Black Sea Fleet was once considered central to Vladimir Putin’s attempted conquest of Ukraine. But that fleet and its accompanying air wing have been battered by innovative Ukrainian missile and drone attacks, turning the once-feared force into something of an afterthought in Europe’s largest war in seven decades. When Putin launched his all-out invasion of Ukraine in February, the Crimea-based fleet was at the center of the action, launching Kalibr cruise missiles at military and civilian targets deep into the country, blocking access to the country’s ports, and threatening an amphibious landing on Odesa. Since those early days, however,...