Depends the player really. Pacioretty had NHL size and strenght from his combine at the draft. Even if a guy like subban or mcdonagh can play in the NHL right now(Mind you not a regular shift), which is possible IMO, it wouldn't exactly do wonders for their development. Some players are raw, some aren't. Some have enough talent to bypass the need for seasoning in the minors. It's the way it is. Patrick Kane doesn't have NHL size or strenght, but hell, he made an impact asap. Generally though, forwards can make the jump easier than d-men and goalies. Then again, it doesn't mean a young goalie/d-man can't make the jump at an early age. People are usually lead to believe they need more seasoning or whatever, true, but while they take longer to develop, it doesn't mean they aren't NHL ready. A guy could play in the NHL for years but peak later, which is usually the case for D-men.