Similar tool-wise doesn't mean much. They are toolsy shortstops, all toolsly shortstops are similar tool wise. How does the fact that Castro is 19, doing well in AA, compared to Ronny being 19 and sucking in A ball not make a difference? Yeah, the similarities are much more than if we were comparing Castro to some left fielder, but other than the fact that they are SS and have similar low walk rates, there are meaningful differences. Contrary to what you said, they don't have similar minimal strikeouts. Ronny struck out a lot, Castro does not. In Daytona Castro struck out 41 times in 358 AB this year, when Ronny was in Daytona he struck out 82 times in 380 AB. That's a fairly huge difference that you not only gloss over but actually contend is a similarity.