While I don't doubt that holds true for some, I think most have been more casual fans in the past since the Rangers have been less than stellar through most of their history. It's hard to get too excited over losing, and only true fans of baseball (in general) want to converse in times of woe, or get so involved in the building process that they understand future ramifications in the daily transactions.
Does that make sense?
We often think of those as bandwagon fans, but in reality many fans of losing teams often find other venues of interest at such times. And I think that explains why many don't know much of anything about our minor league talent, other than those few names the press mentions. (That last statement might be overzealous)