If a team was to tank and end up with the 4th worst record in the league a lot of people might consider that a successful tank job. But in reality, tanking and ending up 5th gives a team the best chance of ending up with the 5th pick.
Tanking and ending up with the 1st, 2nd and 3rd pick gives a team the best chance to end up with the 4th best pick. So, More Banners, I ask you, if you won't tank for the 5th pick, what will you tank for, the 4th pick?