Although Jesus’ family doesn’t explicitly appear in this account of his attempt to minister to the people of his home town, they must have been there, right? In any case, I jumped at the opportunity to bridge the gap between Mary prodding Jesus to perform his first miracle at the wedding at Cana and her later fear that he needed psychological help. Something must have happened in between, and his failure to heal anybody in his return to Nazareth, especially when she was really counting on him to prove himself to skeptical relatives, seemed like it could be sufficient cause.
The other oddity in the reading from Mark is Jesus sending out the Twelve, two by two, immediately after his bad experience in Nazareth. Is this the same story as the sending out of the 70 told by Luke and Matthew? And wasn’t this rather early in his ministry to be sending his disciples out on their own? There’s probably no cause and effect between between bombing in Nazareth and sending out the disciples implied in Mark (where almost the sole rhetorical structure is “and then” – where the “then” isn’t even always a guarantee of chronological succession!) but I found it useful to make that connection as a way of explaining the sending.