The problem with using the "current" rankings is that they are not based on the actual talent level of the farm system alone, but rather the amount of "impact-now" prospects they own. The basis for this discussion was the lack of talent to pull off trades without top guys, but Sickels' and Law's assessment dispels that notion.
The problem here isn't the amount of talent in the system, it's the time it will take to reach the Majors. But that doesn't mean that type of talent is not coveted by other teams.
Look at the Mark Teixeira trade: The "ready-now" piece was Salty, but the near-deal breaker was Neftali Feliz, with the other important part being Andrus. Texas coveted those two, even though they were far-off prospects with the "potential" tag on them, and look at how that turned out.
I have never flat-out said that they're upper echelon. What i have disputed is that the farm is mediocre. There is a significant amount of low-level but high ceiling talent that other teams would find appealing.