He underwent a growth spurt between his junior and senior years, increasing from 6 feet 2 inches (1.88 m) to 6 feet 9 inches (2.06 m), and resulting arm pain as his bones grew faster than his tendons, limiting him to only two innings pitched in his senior year.

He made his professional debut that year with the Elizabethton Twins of the Rookie-level Appalachian League, compiling a 0.47 ERA in 19 innings pitched.

[7] He returned to Fort Myers in 2015,[5] and after pitching to an 8–6 record and a 2.87 ERA in 19 starts, he was promoted to the Chattanooga Lookouts of the Double–A Southern League in August.

[16] He elected free agency on October 1, but later re-signed with the Rays on a minor league deal in the offseason.

[17] On June 28, 2020, Tampa Bay named Slegers to the Port Charlotte team as part of their 60-man roster for the shortened 2020 season.

On August 28, Slegers was sent outright to the Triple-A Salt Lake Bees, however elected free agency the next day.

[22] On August 31, 2021, Slegers signed a two-year minor league deal with the Tampa Bay Rays.

In 2022, he made two scoreless appearances for the rookie–level Florida Complex League Rays, missing the majority of the season due to injury.

[24] On January 19, 2023, Slegers announced his retirement from baseball due to continuing shoulder injury problems.