Minor leagues

The Houston Astros selected James in the 34th round of the 2014 Major League Baseball draft, with the 1,006th overall pick.^[11] James made his professional debut in 2014 with the Greeneville Astros and spent the whole season there, going 1–3 with a 2.72 ERA in 39.2 innings pitched. In 2015, he pitched with the Quad Cities River Bandits where he was 7–4 with a 2.63 ERA in 24 games (18 starts). In 2016 he was promoted to the Lancaster JetHawks where he posted a 9–5 record and a 4.81 ERA in 23 games (19 starts), and in 2017, he went 4–8 with a 4.38 ERA in 21 games, 11 which were starts, with the Double-AA Corpus Christi Hooks.^[12]

After starting the 2018 season with Corpus Christi, James was promoted to the AAA Fresno Grizzlies during the season.^[13] With the two teams he was 6–4 with a 3.23 ERA, and 171 strikeouts in 114.1 innings (13.5 per 9 innings). James was named the Astros' Minor League Pitcher of the Year for 2018.^[14]

During the 2018 season, James saw a jump in his velocity, which he credited to a recent sleep apnea diagnosis.^[15] His roommate in rookie ball in 2014, Ryan Thompson, complained often about James' incessant snoring, saying, "He was like a chainsaw taking down a national forest."^[16] James consulted a sleep specialist in December 2016 and was diagnosed with sleep apnea.^[17] After he began using a CPAP machine, James said he felt "just a little bit more refreshed in the morning, a little bit more refreshed about the day, and slowly I started feeling a little bit better every day."^[17] This translated into a gradual increase in his fastball velocity, growing from 94 to 95 miles per hour to 100 miles per hour.^[17]

Houston Astros

James was promoted to the major leagues for the first time on September 1, 2018,^[18] becoming the lowest drafted pitcher in Houston Astros history to make a start for the team.^[19] In 2018 with the Astros, he was 2–0 with a 2.35 ERA, in six games (three starts) in which he pitched 23.0 innings and struck out 29 batters. (11.3 strikeouts per 9 innings).^[20] James was on the American League Division Series roster but did not see any playing time against the Cleveland Indians. In the 2018 American League Championship Series, James pitched 4.1 innings, giving up 6 hits and 4 runs and striking out 7.^[21]

In game 4 of the 2018 ALCS, James recorded his highest velocity fastball, clocking in at 102.4 miles per hour and striking out Rafael Devers.^[22]

In 2019 with the Astros, he transitioned from the starting rotation to the bullpen. On July 15, James served in an opener role, pitching a 1-2-3 first inning and recording one strikeout.^[23] On September 3, 2019, he recorded his first career save against the Milwaukee Brewers. He ended the 2019 season 5–1 with a 4.70 ERA in 49 games in which he pitched 61+1⁄3 innings and struck out 100 batters (14.7 per 9 innings).^[24] James was also a part of the ALDS, ALCS, and World Series rosters and is formally credited with the win in game 3 of the World Series, making him one of only 10 pitchers in Astros history to record a World Series win as of November 2022.^[24]

During spring training in 2020, James was part of a battle for the fifth spot in the starting rotation, a role he eventually won. After arriving to the pre-season camp late due to the birth of his daughter, James made two starts at the beginning of the delayed 2020 season before transitioning back to the bullpen. On August 20, he left a game against the Colorado Rockies with left hip discomfort and was placed on the 10-day injured list on August 22. James was activated on September 9 and posted a 1.35 ERA and 0.90 WHIP over his 6.2 innings of work in the month of September.^[21] He was placed on the COVID injured list due to health and safety protocols on September 25. On the year, he went 1–0 with a 7.27 ERA with 21 strikeouts in 17+1⁄3 innings (10.9 strikeouts per 9 innings), over 13 games.^[21] In his 4.0 innings of work in the 2020 postseason, he allowed 5 hits and 4 runs. Notably, James gave up a game-tying home run to Ji-man Choi in Game 5 of the 2020 American League Championship Series.^[25]

On October 24, 2020, it was announced that James had undergone surgery to repair a labral tear in his left hip and would be out for 6–8 months.^[26] In a spring training broadcast in March 2022, it would be revealed that James had also received a PRP injection in his right elbow at this time. Originally set to return between late May and early June, he was retroactively placed on the 60-day injured list on May 26, 2021, as he continued to recover from the surgery.^[27] After completing rehab assignments with the Fayetteville Woodpeckers and Sugar Land Skeeters in the month of July, James was activated off the injured list on August 1 and optioned to Triple-A Sugar Land. In his 20.2 innings in the minors in 2021, he allowed 7 earned runs and struck out 28.^[28] James was recalled on August 31 and was optioned back to Triple-A on September 5. He was optioned and recalled two more times in the month of September. James had a 5.40 ERA in his 5.0 major league innings in 2021.^[29] In his final appearance of the year for Sugar Land on October 3, he gave up 3 runs and left the game with an injury after hitting a 20 pitch limit.

James avoided arbitration with the Astros on March 22, 2022, agreeing to a $800,000 contract for the season.^[30]

On March 30, 2022, James was optioned to Triple-A Sugar Land, now called the Space Cowboys, after two major league spring training appearances.^[31] On April 10, he closed out the team's first win since rebranding, simultaneously picking up his first save of the year.^[9] On June 15, James left a Sugar Land game with an injury and was placed on the 7-day injured list with a right lat strain on June 21 before being placed on the 60-day injured list on the 23rd.^[29] He began a rehab assignment with the Fayetteville Woodpeckers on August 25, striking out the side in his 1.0 inning of work.^[32] After making 7 rehab appearances (2 in Fayetteville and 5 in Sugar Land), James left the September 13th Sugar Land game with an apparent injury, indicated by a dropoff in his fastball velocity. On October 1, it was announced that James had undergone surgery on his right flexor tendon.^[33]

On November 18, 2022, the Astros non-tendered James, making him a free agent.^[34]

St. Louis Cardinals

On January 26, 2024, James signed a minor league contract with the St. Louis Cardinals and was assigned to the AAA Memphis Redbirds.^[35]