In spring of 2015, imagine if someone had said that Kris Bryant was the National League's best third baseman. That would have been met by some resistance, because at that point Kris Bryant had not yet been a National League third baseman. People would have wanted for Bryant to prove himself and would have instead put forward David Wright or Nolan Arenado or other more established guys. Guys who had already played third base in the NL. But sometime in 2015, Bryant became the league's best third baseman, and it stands to reason he was already the best when he made his debut. But when it comes to predictions, some people have an aversion to risk and pick what's familiar.
Fast-forward, switch leagues and switch positions. In the latter part of 2016, Yankees catcher Gary Sanchez hit 20 homers in 53 games and made a late push for the American League Rookie of the Year award. But some needed to see him play more than barely one-third of a season.
While he didn't take home the trophy, what Sanchez did in that short time was make a compelling case that he is already the best catcher in the American League. Again, part of the counterargument is that Sanchez hasn't done enough. But how much should that really matter? Put it this way: Which AL catcher would you take right now? Forget any long-term considerations. Who would you take for one month or one season? Sanchez has to be right there.