I know where you're coming from, but disagree. At one point Walter Johnson was a prospect, and if the BP's of the world had projected him to be better than veteran pitchers x, y or z, they would have been dead on correct.
I don't really buy the begrudging "you have to prove it to me first" line of thinking, else what's the point in even scouting or ranking players, or projecting their potential? Of course he hasn't proven "anything" yet in terms of facing major leaguers, he's young and hasn't had the chance yet. Goldstein and the rest of the scouts and prognosticators are simply making forward looking projections of where they think the player may end up, and hindsight is not available.
When the Big Train was a prospect, the minor leagues as we know them didn't even exist.
In July of 1907, I doubt that there was anyone who was saying that Johnson rated higher than Honus Wagner.
