The Boston Red Sox selected Light in the first round of the 2012 MLB draft. Light made his professional debut in 2012 with the Short-Season A Lowell Spinners, where he posted a 0–2 record with a 2.37 ERA in 12 starts, allowing eight runs on 27 hits and five walks, while striking out 30 in 30⅓ innings of work. He then joined the Low A Greenville Drive in 2013, but suffered a partial tear in his right hamstring that was initially misdiagnosed before all-but-ending his season in early June. He returned in late August for a rehab assignment with the GCL Red Sox, where he pitched six innings of shutout ball in three appearances. Being limited to 28⅓ innings at Greenville, he went 1–4 with 28 strikeouts and an ERA of 8.06. Light returned to Greenville in 2014 and earned a promotion to the High-A Salem Red Sox during the midseason. He went 8–6 with a 4.83 ERA in 25 starts between Greenville and Salem, striking out 76 batters while walking 37 in 132⅓ innings. After making 49 starts over his first three seasons, Light was told he would be changing roles and throwing out of the bullpen when he reported to Double-A Portland Sea Dogs to open the 2015 season. With the Red Sox relief pitchers finishing last in fastball average velocity in 2014, and giving another hard-throwing prospect Matt Barnes a chance as a reliever, the organization decided to increase velocity out of the bullpen more than it had before. Light delivered a solid start to his 2015 season after being moved to the bullpen. He now regularly reaches 94–96 mph with his heavy fastball, reportedly touched 100 mph at times, and reintroduced a splitter, which he had used successfully before being drafted in 2012. As a result, Light went 1–1 with a 2.43 ERA and three saves in 21 games at Double-A Portland, allowing 11 walks and striking out 32 in 29⅔ innings, while holding opponents to a.168 batting average. He then earned a promotion to the Triple-A Pawtucket Red Sox in the month of June. Light was 3–5 with five saves and a 3.88 ERA in the two stints, totaling 62⅔ innings pitched to go with 67 strikeouts and 37 walks. Light opened 2016 at Pawtucket. He was promoted to the Boston Red Sox on April 24. After giving up six runs, including two home runs, in a July 2 game against the Los Angeles Angels of Anaheim, he was demoted back to Pawtucket.
On June 17, 2017, Light was claimed off waivers by the Seattle Mariners. He was released on April 19, 2018.
Player profile
Light had a 90–95 mph heavy fastball which can top out at 97 mph. He also has an 85–87 mph slider, while a 79–81 mph changeup is a work in progress. He was projected as a reliever, with great potential as a setup man or closer.