Not being ready to help a NBA team win can be said for almost all rookies. Even an all-time great like Durant wasn't ready to help Seattle win his rookie season. The players who are ready tend to be bigs who can be immediate defensive forces like Duncan (even without Robinson, he would've been highly influential) and Dwight Howard or point guards/point forwards like Paul, Lebron and Wade (who was a point guard his rookie season).
Durant was a good scorer but didn't have much impact on defense or as a passer so his overall impact was blunted. I see Parker in the same way his rookie season with less effective scoring. Wiggins looks capable of playing good defense from the start but his scoring and passing might not even be average. Embiid looks a little too skinny to have the kind of defensive impact he might have several years from now. There's bound to be a lot of ups and downs as he wrangles with players who are just as big as him and stronger.
I'd peg Smart as the player who helps his team most his rookie season, provided his shot is better. I don't think there is anything wrong with his stroke so with lots of repetition and NBA instruction, I can see his shot being a lot better. With an average shot, he could be the kind of advanced player who upgrades his team a good amount.