He moved to California when he was young. It's not hard to imagine the surprise and delight the audience felt upon learning that the hero Marion Morrison was really the big guy who later dispatched hundreds of assorted train robbers, cattle rustlers, and other bad guys. It seems likely that the audience listened with anticipation to the rest of the speech. Here's another example of dramatic surprise. Let us hope that this association will be as youthful and vigorous in its fiftieth year as Mickey is today.
Good transitions are important in any kind of writing, but especially in speeches.
If you're writing an article or a book, you can use subheads, bullets, or other typographical devices to tell the reader you're changing subjects. In a speech, you must find other ways to make your transitions. Sometimes a slightly exaggerated pause or emphasis of a word or phrase serves as a transition. An even longer one might be equated with a typographical bullet. Without transitions, your speech can seem choppy or jarring.