It was also often thought that how a person died revealed the most about that person's character. This becomes a crucial matter for a gospel writer such as Mark, because Jesus died by the most humiliating means then available: crucifixion. It would require a lot of explanation in antiquity to explain how God's Son could end up on a cross, for normally such an end would suggest he was a wicked man, a person of bad character. I would suggest that the reason Mark spends one third of his narrative (Mark 11-16) on the very last week of Jesus' life is that there was much to explain about Jesus' demise if one was going to conclude that Jesus was a good person, let alone if one was going to argue he was the Son of God.
Besides a need to do apologetics in regard to Jesus' death, two other important factors strongly affected how Mark structured his gospel. The first of these was Mark's apocalyptic worldview. The word "apocalyptic," from the Greek apocalupsis, refers to the revelation of things, including secrets, that were hidden. Mark believes that in a dark and fallen world, it would not be self-evident to fallen persons that Jesus was the Christ, the Son of God. This truth had to be disclosed or revealed in a series of epiphanic moments if human beings were to know it.
Thus, in six places carefully spaced out in his gospel, Mark provides us with an account of these disclosure moments. (Of course, the reader of Mark's gospel knows from the very first verse that Mark is going to convey good news about Jesus as the Christ, the Son of God.)
The second major disclosure moment in the gospel comes at the climax of the gospel's first half, when Peter, as representative of the disciples, confesses that Jesus is the Christ, the Son of God (8:27-30). That story ends with Jesus telling the disciples not to disclose this truth yet. The world is not ready to hear it.
The third disclosure moment occurs shortly after Peter's confession, when we hear about the Transfiguration of Jesus and his appearance with Moses and Elijah on a mountain (9:2-9). Here again, the heavenly voice reveals to the inner circle of the disciples that Jesus is God's beloved Son, and so he should be heeded.
The fourth disclosure moment does not come until the end of the Jewish judicial hearing, when Jesus is asked if he is the Christ, the Son of God, and he replies in the affirmative but qualifies his answer by making clear that he would prefer to call himself the Son of Man who would one day come on the clouds as the judge of even his current judges (14:61-62).
The fifth disclosure moment comes when Jesus is on the cross, and a Gentile centurion guarding him has an "aha" moment. Noticing how Jesus died, he says, "Surely this is the Son of God" (15:39).
Finally, there is the disclosure at the empty tomb on Easter morning by an angel to the women, but this disclosure is more about what has happened to Jesus than who he is--he is now the Crucified but Risen One (16:6).
Notice that the disclosure moments for the disciples cluster in Mark 8-9, at the climax of Jesus' Galilean ministry, before he went up to Jerusalem. This is because of the third major factor that determines the structure of Mark's gospel. According to Mark's way of evaluating Jesus' life, if you are to understand his ministry, and especially if you are to understand why he had to die on the cross, you first need to understand who Jesus was--the Christ, the Son of God.