G has averaged basically one more assist per game over the last two seasons than Cooney. Considering G played probably half his minutes at PG last season and almost all his minutes there this season, I'd say that alone indicates he's not a particularly skillful passer. You're almost guaranteed 3 or 4 assists per game just by virtue of being the guy who dribbles the ball up the court. Neither player has great court vision and neither creates well for others.
Going with the eye test, G does not convert many difficult passes and turns the ball over at a pretty high clip. Bottom line, Cooney and G aren't great distributors and it probably wouldn't have mattered which one was in there for that specific play. Considering Wisky made it a point of emphasis to keep G out of the lane, unlike Cooney, I think Cooney was the smart play.