The first seventeen verses of Matthew deal with three separate occurrences in the ministry of Jesus.
The first is the healing of a paralytic man, the second is the calling of Matthew followed by the reprimand of the religious leaders because of their complaining about Jesus' association with tax collectors and the other ilk of society. The third is about John's disciples complaining Jesus' disciples do not fast as they should. The result of this encounter is the telling of the parable of the wine skins.
While on the surface these three stories do not seem to be related to each other, they all have something in common, faith, forgiveness and a new life.
Matthew wrote his gospel primarily to prove to his fellow country men to prove the divinity of Jesus'. Each segment of the Gospel is clearly written towards that purpose including Matthew chapter 9. The first two stories show the faith of Jesus' followers, first the paralytic man and then Matthew himself. This faith results in the forgiveness of sin and the healing of mind, body and soul. Matthew, declares to his readers, in a few words, Jesus' power as God, to forgive sin and heal the sick in body and soul.
The third story was meant to show the result of faith and forgiveness. Jesus as Matthew shows did not come to abolish the old ways, like fasting and prayer but to insure each disciple practices them more intelligently and with the idea in mind that a new age has come, a new life has begun.
John's disciples it seems were caught up more in the ritual of fasting, (the old wine skins) then in the attitude of fasting (the new wine). Matthew shows that once someone has a faith, in Jesus and lives under His forgiveness then the old has gone and the new life has begun. Old attitudes do not hold fast when the new life is poured in them.
Truly, Matthew declares to his fellow country men in these verses seek Jesus in faith, find forgiveness and live the new life, a life under the Son of God.