I like the idea of this system, but it heavily favours scorers. Blocks and steals should be weighted much higher than points, they are rarer and deny the opponent a look at the basket while creating an extra look for your side.
Effectively the weighting you have is 1 vote per point scored, which makes 12 points (average game) equal to 10 boards (good game) and 8 assists (very good game).
It’s be good to see the pts diff factored in, too. This would allow players on better sides to be favoured, sure, but also reward guys carrying their team as they’d get a better result even if their side gets scored on heavily when they go off.