If you go by record, the 2014-2015 Golden State Warriors were the best team in NBA history; then they added Kevin Durant. They lost nine games. A mere nine losses in an 82 games season is an absolutely incredible feat for the team.
The title is a bit misleading. It’s not the Golden State Warriors were either lucky or good, but rather that Kevin Durant made them arguably the best team this generation and the NBA as a whole had ever seen.
But, were they a combination of both good and lucky before Durant? I tend to say no.