It's interesting. I looked into the site and it seems reputable, but their predictors are qualitatively pretty weak. Their regression model includes age, height and weight, college statistics, and his top 100 ranking (per Ford). They claim their model is novel (and better) because they include some regressor that takes into account the opportunity they will get to play, if I'm not mistaken. They're vague, and perhaps I'm misunderstanding their approach, but they don't indicate at all how they did it.
Beyond that, for a statistics website (not specific to bball), one would expect to see variance accounted for using their model. There isn't reported, which gives no indication whatsoever of how accurately they can predict NBA success. It's a good idea, no doubt, but we don't appear to be anywhere near this, yet. Not sure if we will be, given so many other variables that we either wouldn't be able to collect data one or quantify (e.g., personality traits, bball IQ).