Once upon a time, Evgeni Malkin scored 47 goals and 106 points in a season. His linemates were Ryan Malone and Petr Sykora. Neither of them scored 30 goals.
But wait! The next season, Evgeni Malkin won the Art Ross and the Conn Smythe. He had 113 points. Wherein the best regular linemate he had was still Petr Sykora, and his regular linemates in the playoffs, in which he won the Conn Smythe, as a reminder, were Maxime Talbot and Ruslan Fedotenko.
In other words: it does not necessarily follow that James Neal was the "best" option for Malkin, because there have been equally good - if not better - seasons with Malkin flanked by less talented but more complementary players. And - the two years I mentioned, Malkin was a juggernaut both regular season and playoffs, and we made the finals both years.
It does not necessarily, logically, follow that Neal was not a good fit for Malkin to put us over the top and win in the playoffs due to the above. But, similarly, your premise doesn't work either - nothing proves that Neal was the ideal fit for Malkin, except for regular season points,[/B] which, as you may note, have nothing to do with the playoffs, either.