How important is a great farm system?

This might be viewed as a continuation of my last post explaining why I never got on board with John Coppolella as a general manager, but it's also more than that.
With Coppy and among the Atlanta Braves' fan base, there seems to be an obsession with farm system rankings. For fans of such a franchise, I can see the appeal to this focus. Since the organization is rebuilding, the major league team stinks, so why not focus on the minor league talent?
And while this post isn't a criticism of that focus, it does seek to address how much value farm rankings actually have.
So I used Baseball America's annual Organization Talent Rankings to see how often high-ranking farm systems linked with future championships. The results were interesting.
From 2005 to 2015, 25 total teams had farm systems that ranked in the "top 5" farm systems at some point. From that group of 25, just four teams managed to win a World Series at any point after reaching that point of the rankings - the Red Sox, Cubs, Giants and Royals. Of those, only two - the Cubs and the Royals - won a World Series after having the best farm system in baseball, a distinction the Braves reached last season.
Now you may have noticed the same thing I noticed, though. While that ratio of World Series success to farm system ranking is pretty low, those four teams have accounted for seven of the 12 World Series titles in that time. That would suggest that if you can really master the farm system building, you can have consistent success.
As true as that could be, let's look at the other end of the spectrum. In all, 23 teams have found themselves in the "bottom 5" of the list in that same time period. Of those, three teams - the Cardinals, Giants (again) and Cubs (again) have won World Series rings after hitting the basement region to account for six of the 12 rings. The Cardinals managed to win a World Series both after hitting the "bottom 5" AND after having the worst farm system in baseball in 2005.
In fact, let's take a minute to look at the Cardinals. Now, I know a lot of Braves fans have a particular distaste for this franchise, but few could question their success at the major league level.
In fact, St. Louis has been perhaps the modern prototype for consistent success. From 2000 through 2017, the Cardinals have had just one losing season. They've won two World Series titles in that time, been to the World Series two more times and won their division 10 times.
Yet, when you look at the farm system rankings from 2001 through the Cardinals' most recent World Series championship in 2011, their best ranking was eighth. Beyond that, their farm system was ranked in the "bottom 5" a total of five times over that stretch.
The Cardinals did manage to make it to the top of the ranking in 2013 and made the World Series that year, for full disclosure.
But what does all that mean? For me, it means that it is absolutely possible to turn a great farm system into a great MLB team. But it's also absolutely possible to build a great MLB team without having a high-ranking farm system, and there's also success to be found in between.
It's how that talent is developed, identified and utilized that matters, and it should mean that if the Braves need to make moves that bring greater balance to the system but perhaps hurt talent rankings, they should pull the trigger.