Let's all remember a few things:
1) Greening got to play hockey at the highest level while getting paid handsomely to do so. Most of us slug away at jobs that drain our souls for a fraction of the money he made. How many of you would love, love to play a game as a way to make a living? He did, no matter how long it lasted.
2) While it's too bad he never evolved, or couldn't evolve, his game, getting demoted happens. He isn't the first guy to have shown promise, get a great contract, and then slowly fade out of the league... and he won't be the last.
3) There are indeed all types of intelligences (they ram the concept of 'mutliple intelligences' down the throats of all teacher's college students to help teachers realize that students are all often smart in their own way), and he has shown that, in the NHL, he doesn't quite have the level of intelligence that other players do. I'd wager however that if you (the general 'you' on this board) stepped on the ice with him, you'd be shocked by how 'intelligent' he is on the ice. Just compared to other NHLers, he's not quite there. He's also smart enough to have made it through a tough program at a good school, so he's got book smarts which can translate well in real life. Assuming anything about his intelligence off the ice is ridiculous and is of no value in this discussion.
4) He seems smart enough (and with the assumption that he applied theory to practice from his university studies) to have done smart things with his money... Broke 30 for 30 dealt with a lot of types of athletes... but rarely do you hear of a hockey player who has squandered millions away the same way other athletes have. If he was truly smart, he would have given himself an 'allowance' out of his salary... a friend's cousin who played close to 10 years in the NHL as a 4th line guy did this with the help of his father (someone with financial know-how)... his 'allowance' was a ridiculous amount of money compared to what I get to play with... and now he never has to work again if he doesn't want to, the money he saved is working for him.
5) This was way too long. Those of you who made it through this... thanks for reading.