The Braves drafted Sims out of Brookwood High School in Snellville, Georgia with the 21st pick of the 2012 draft. They sent him to their Gulf Coast League team, and he excelled there, earning a promotion to Danville to finish the season. All told, he made 11 starts in his draft season with a 3.71 ERA, 1.21 WHIP, and 13/39 BB/K ratio over 34 innings. While he didn’t make any top 100 lists, he certainly got the notice of quite a few national writers who raved about his raw stuff.
Sims pitched the entire season for the low-A Rome Braves team, going 12-4, with a 2.