Sims was added to the Braves' 40-man roster on Friday.
The 22-year-old had a rough stint with Triple-A Gwinnett, but his 2.67 ERA and 10.0 K/9 at the Double-A level opened some eyes in the organization, leading Atlanta to protect him from the Rule 5 draft. Sims' nasty fastball/curveball combination could allow him to dominate in a high-leverage role if the Braves decide to pull the plug on developing him as a starter in 2017.