No, you misunderstand. As you get older or sustain injuries in the game, your reflexes become slower. Also, if you are outnumbered, your reflexes are artificially lowered. So in effect, you can't win anymore and need to change strategies. For example, by shooting up a ship and waiting for them to strike their colors rather than boarding for a sword fight. Consequently, if you haven't taken out the other pirates while young-ish, it becomes impossible. Some swords are faster than others, too.