I would not have thought it contentious to describe a relative political outsider winning over forty percent of declared delegates "successful". If insisting upon this will cause unnecessary distress, I am happy to amend my claim to "as successful as he has been". But the point remains unchanged: Sanders has successfully appealed to sections of the electorate who are either disenchanted with the Democratic leadership, or actively hostile to it. He did not create this sentiment, he has simply given it voice at a natural level. Pretending that this is not the case because admitting as much is inconvenient for your short-term political goals is, at best, naive, at worst, wilfully self-destructive.