Would Yamato have made a difference if Japan had managed to deploy her effectively?
Short answerPotentially at Midway if committed with effective air support; in its later historical employment, probably not.
NotesThe answer separates the ship's theoretical power from the way Japan actually employed it. A timely deployment for Midway, especially as part of a force with a full air group, could have influenced the operation. In its later historical employment, Yamato functioned largely as a prestige image rather than an asset changing events. A capital ship's value depends on when, where, and with what supporting force it is committed.