The quick summary: above-average first basemen hit generally hit for more power in their age 19 seasons than Smith has shown this year with Savannah. Some of Smith's output has to do with Grayson Stadium, but even his road performance is pretty far below the average of the group in terms of key offensive indicators.
So, onto the mailbag:
The short answer is that including only the performance of above average MLB first basemen in 2014, who were playing in a full-season league at age 19 does not change the conclusions much at all.
Here's the key chart comparing Smith to the above average first basemen in MLB and their performance in their age 19 professional seasons.
(Full Season Only)
Note that some of Smith's "missing" extra-base hits are showing up as singles. He's making hard contact but not driving the ball.
The optimistic take is that he's not going to fight Grayson Stadium's enormous right-centerfield gap and instead is working on spraying the ball up the middle. The pessimistic take is that he's doing so because he lacks a skill other successful first basemen had already started to put into game action at this age. The optimistic take is that Brandon Nimmo went from two homeruns in 110 games with the Gnats in 2013 to 10 homeruns in 113 games split between advanced-A and double-A. The pessimistic report is that Nimmo is three inches taller, and generates better leverage in his swing.
Smith can hit, but the question about his ability to hit for power in the big leagues is real and it certainly will not be settled in 2014 when he's in a-ball, years from the big leagues and still learning how to hit.