I agree you look at that but his value to the TEAM is affected by the value that other players bring. If your RF is an all average no power player and your SS is an all defense no offense player it puts a lot of pressure on other positions to produce offense. If your RF brought more production to the table then it makes it easier to carry the no offense of the shortstop.
Also, and this doesn't necessarily mean anything for the Braves, but advantage gained from the range of the shortstop diminishes if you have great range at 3B and 2B. I know that sounds counterintuitive since an infield defense made up of great defenders is less likely to allow ground balls through. BUT, if the shortstop is getting to balls that the 3B would have gotten to then the value of that play is less.
I understand needing a metric to value a player as an individual but you can't stop there you also have to value the fit to the whole.
Which can be countered that the 3B can get more balls to this right than he normally wouldn't. You see this quite often in the outfield. Having a plus centerfielder generally increases the defensive value of the corner spots.