Bu the every possible metrics.

Critical reception? Sales? 

Yes, critical reception of gaming receiver and players itself.

How do you quantify player reception outside of sales numbers though?

I quantify player reception from players that played game obviously. Zelda is game for just Nintendo platform and game itself isnt so wide appealing like Mario for instance.

I wouldn't take player reception seriously when it comes to Zelda, because these games have always some kind of delayed recognition. It took years from some gamers to achieve likeable status, like Wind Waker or Skyward Sword. They're a volatile metric that doesn't reflect reality once everything is done.

This happens with a lot more games, too. Few ones managed to be loved from beginning to the End of Times 

But how do you plan to determine player reception? A survey? A poll? Forum chatter?

Critical reception is quantifiable, as measured by Metacritic. That then you run into the problem that by that definition, some of the "biggest" games of the generation are low profile indies.

Look, I get that for you (and even for me) Zelda will be one of the biggest games of the generation, but for most gamers, it will not be.

Yes, by everything.

Indies became popular last 2-3 years, I am talking about 30. years old series. And enewhone can make difference between Indie game and AAA game, there is a reason why Indie games having price of few bucks and other game price of $60.

Of Course not, and that's why I wrote critical reception of gaming reviewers and players itself. If you have gaming reviewer's and people who played game itself and bouth are saying that Zelda U is one of biggest games of generation, than that game is one of the biggest or best game of generation.

I'm sure it will be well reviewed and well liked by most of the people who played it. But the simple fact is, most gamers are not going to play it, or even care about it. It's just not the huge mainstream franchise it was a decade ago.

Well simply fact is that any exclusive isn't played by most of gamers, we can only say that for multiplatform games, but that doesnt mean that games that are not multiplatform games cant be one of the bigest games of generation.

If you think on sales when you say "huge mainstream franchise like it was a decade ago", I think there are again good chances that Zelda U have great sales like TP, because probably again like TP Wii Zelda U will be launch title on completely new platform and in same time will lota a Wii U owners will buy game too.