How do you know the best group?

With the recent Yankees addition of Jacoby Ellsbury, some people are wondering if Gardner-Ellsbury-Ichiro could be the best defensive outfield ever. Whether it is, or not, it got me wondering what it means to have the best group.

I'm reminded of when Curt Schilling was traded to the Diamondbacks. People wondered if he and Randy Johnson were the best pitching tandem in baseball. ESPN even put out a poll. You could choose between them, or a couple of the Yankees starters, and probably a couple Braves starters. The one that got a lot of votes was "Pedro and any other Boston pitcher." the theory being that Pedro was so great, he carried whichever guy he was paired with to the top. And, he probably would have. But, does that make a good duo?

Or another example that has popped up recently when you talk about all the championships Boston has seen lately. Is this the best stretch ever? Well, not if you just count rings. After all, the Celtics of the 60's have that beat just on their own. But, do you have to somehow take into account the breadth of greatness? That all four teams have rings? Does there have to be some sort of standard deviation involved?

Back to the outfield. How do you pick the greatest outfield of all time? How about just the greatest Red Sox outfield? Do you just take one with Ted Williams or Babe Ruth in it, and call it a day? Or, would a more well-rounded version be better? Sure, if you add up the WAR for a Rice-Lynn-Evans outfield, you might not even reach Ted's WAR on his own. But, does the fact that they're all equally contributing have to count? Do you have to go look at the Golden Outfield with two future Hall-of-Famers on it? Is Williams+2 still better?

So, what do you think? Is the best outfield the one with the highest average member?

Or is it the one with the best outfielder?