The value of a good farm system

The Baseball Analysts have an eye-crossing article explaining the value of a "good farm system," using Baseball America's projection system, in which the Rangers have the #1 overall farm system, while the Astros sit at #30. There are charts and graphs, and the money quote:

Since the Rangers' system was rated #27 as recently as 2008, the expected farm impact in 2010 is small. However, the impact increases dramatically starting in 2012. Overall, over the next 9 years, the Rangers farm system will likely net them 31 extra wins, meaning that while their system won't have a huge effect in any one particular year, it's likely to have a strong impact on the Rangers franchise over the next decade...

...For the Astros, it's nearly the opposite situation. Their farm system projects to cause them to lose over 36 games over the next ten years. So, is the difference between the Rangers and Astros farm systems really 67 wins over the next nine years? It would appear that way, although there are some caveats. For one, the year-to-year farm system rankings are correlated with one another, so the fact that the Rangers have a good farm system now is also indicative that they will have a good system in the future. That undoubtedly accounts for some of the large difference in wins. While the Rangers may not be still reaping fruit from their 2010 farm system in the year 2018, the fact that they have a good farm team now bodes well for their future farm teams, and hence their future major league teams.

What to make of this? David Coleman, over at The Crawfish Boxes makes a good point:

For instance, when the Astros picked Jason Castro over Justin Smoak in the 2008 draft, analysts ripped them left and right. Smoak then flew through the minors and is listed by at least one publication as one of the top 10 prospects in baseball. Castro has also risen quickly and, while highly rated, isn't viewed with the same kind of respect as Smoak, which is one of the reasons why the Rangers are ranked first in BA's list. Smoak, though, would be blocked by both Carlos Lee and Lance Berkman. If Wade and Co. made the decision after 2010 to let Berkman walk for Smoak, he'd be roasted over the coals in Houston. Drafting Smoak would have created an unnecessary surplus value. Drafting Castro gave the Astros a solid prospect who should impact the major league roster this season at a position that is not only more scarce than first base, but is also an organizational need. In this situation, shouldn't more credit be given to the Astros farm system for producing a player that helps an area of weakness for the major league club?

That's the main thrust of my disagreement. While BA's rankings do seem to have some predictive power, I'd feel better knowing a little more about what goes into those rankings.

I totally agree with Coleman's thoughts. Having eight unbelievable first basemen doesn't do you any good, but having good players across the board is better for the health of the Big Team. Depending on my motivation level, it would be fun to go through and see who John Sickels at Minor League Ball graded as each team's "Top Prospects" and where the team's needs project in 2-3 years. But my motivation level is fickle.