[3] Kelly spent the year with the High–A Myrtle Beach Pelicans, making 40 appearances and posting a 3.95 ERA with 64 strikeouts in 82.0 innings of work.

[5] For the next two seasons, Kelly pitched in relief with the Texas League Champion Double–A San Antonio Missions and Triple–A Tucson Padres.

[1][7] He made his major league debut on June 30 against the Washington Nationals, pitching one inning, in which he gave up one run on two hits, while recording a strikeout and a walk.

[citation needed] In 15 appearances for the Lions, he compiled a 2–2 record and 4.19 ERA with 20 strikeouts and 3 saves over 19+1⁄3 innings pitched.

He pitched in relief for the Triple–A Tacoma Rainiers & Double–A Arkansas Travelers, finishing the season with 2.97 ERA, 32 strikeouts in 30+1⁄3 innings, and an .86 WHIP with 6 saves.

[14] Kelly continued putting up good numbers in 2017 when he signed on for the off-season first half with Cardenales de Lara in Liga Venezuela Beisbol Professional.

Kelly again pitched for Cardenales de Lara in 2018 winter season and on November 20, 2018, converted his 19th consecutive save, a club record.

[16] On July 14, Kelly earned his 100th professional career save with three strikeouts in the ninth inning to preserve the 3–1 Patriots victory.