San Francisco Giants Loáisiga signed with the
San Francisco Giants as an international free agent on September 23, 2012. He made his professional debut in 2013 with the
Dominican Summer League Giants and spent the whole season there, posting an 8–1
win–loss record with a 2.75
earned run average (ERA) and 1.11
WHIP in 13 games started. He did not pitch in 2014 and 2015 due to injuries, and the Giants released him on May 30, 2015.
New York Yankees Loáisiga signed with the
New York Yankees on February 9, 2016. He began the season with the
Charleston RiverDogs, and after pitching one game, he suffered an injury which required
Tommy John surgery. The Yankees added him to their 40-man roster after the season. He returned in 2017 and pitched for both the
Gulf Coast League Yankees and
Staten Island Yankees, pitching to a combined 1–1 record and 1.38 ERA in 11 starts. Loáisiga began the 2018 season with the
Tampa Yankees of the
Low-A Florida State League, and earned a promotion to the
Trenton Thunder of the
Double-A Eastern League after starting the season with 3–0 record with 1.35 ERA over four starts. In Trenton, he made six starts, compiling a 4.32 ERA, however impressed by striking out 32 batters in 25 innings of work. After Yankees starter
Masahiro Tanaka was injured, Loáisiga was called up to the majors, skipping the
Triple-A level. He made his major league debut on June 15, 2018, during which he pitched five scoreless innings, and earned the win. He was also the first
Nicaraguan to play for the Yankees. He made four starts for the Yankees, pitching to a 3.00 ERA, and was optioned to the
Scranton/Wilkes-Barre RailRiders of the Triple-A
International League on July 2. He was recalled to the Yankees on September 2 after roster expansion. In total he pitched innings for the Yankees in 2018. He followed it up in 2019 with innings across 15 appearances for the Yankees. In 2020, Loáisiga broke camp with the Yankees, again serving as a swing man, starting occasionally and also coming out of the bullpen. On April 24, 2021, Loáisiga recorded his first career save against the
Cleveland Indians. Two months later on June 25, Loáisiga became the first relief pitcher in Yankees history to
strike out four batters in one inning, striking out
Michael Chavis,
Alex Verdugo,
J. D. Martinez, and
Xander Bogaerts of the
Boston Red Sox in the seventh inning. In July 2021, Loáisiga, along with teammates
Nestor Cortes, and
Wandy Peralta tested positive for
COVID-19, causing the Yankees to put him on the COVID-19 injured list and the MLB to postpone the game against the
Boston Red Sox to the start of the second half of the season. Loáisiga finished the 2021 season with 18 holds, a 2.17 ERA and 69 strikeouts in innings. In 2022 he was 2-3 with a 4.13 ERA. On May 1, 2023, it was announced that Loáisiga would be out until August after undergoing surgery to remove a
bone spur from his right elbow. On August 7, Loáisiga was activated from the injured list. In 17 relief outings, he logged a 3.06 ERA with 6 strikeouts across innings pitched. Loáisiga made three scoreless appearances for the Yankees to begin the 2024 season. However, he was placed on the 60–day injured list with a right flexor strain on April 5, 2024. The next day, it was revealed that Loáisiga had a torn
UCL in the right elbow, requiring surgery, and prematurely ending his 2024 season. On December 11, 2024, Loáisiga signed a one-year contract to return to the Yankees with a club option for 2026. In 30 appearances for New York, he registered an 0-1 record and 4.25 ERA with 25 strikeouts and one save across innings pitched. On August 28, 2025, it was announced that Loáisiga would miss the remainder of the season due to a flexor strain. The Yankees declined his club option on November 5, making him a free agent.
Arizona Diamondbacks On January 13, 2026, Loáisiga signed a minor league contract with the
Arizona Diamondbacks. On March 25, the Diamondbacks selected Loáisiga's contract after he made the team's Opening Day roster. ==International career==