[2] The Kansas City Royals selected Gray in the 13th round of the 2010 Major League Baseball (MLB) Draft, but he did not sign.

[1] For Eastern Oklahoma, Gray pitched to a 6–2 win–loss record and a 2.89 earned run average (ERA).

[7] Gray was expected to be among the first players chosen in the 2013 MLB Draft, and was considered by the Houston Astros, who had the first overall pick.

[18] Focusing on his fastball and slider, Gray pitched to a 0–2 record and a 5.53 ERA in nine starts for the Rockies.

[20] On May 13, Gray earned his first career major league win in a 5–2 victory over the New York Mets.

[24] On July 5, Gray hit his first career home run off of Cincinnati Reds pitcher Scott Feldman, which measured 467 feet (142 m).

The Rockies did not include Gray on their postseason roster for the 2018 National League Division Series.

[30] In August 2019, Gray's season ended due to the diagnosis of a stress fracture in his left foot.

[31] In 2020, Gray's season was cut short due to right shoulder inflammation as he pitched in only eight starts.

[36] He returned to make his second start for Texas on April 19, and went back on the injured list with a sprained medial collateral ligament in his left knee.

[38] Gray pitched three scoreless innings in relief in Game 3 of the 2023 World Series, earning the win.

Gray started the 2024 season off well but was removed from a game on May 21[39] and was later diagnosed with a mild right groin strain, landing on the 15-day injured list on May 23.

[47] His brother, Jack, played linebacker at Northeastern State University, and is currently one of the football coaches for their high school in Chandler.