Donnelly originally signed as a catcher with the Twins in 1967 and played four seasons in the Minors before getting into coaching.
Former Mariners bullpen coach Jaime Navarro, who was the bullpen coach on Eric Wedge's staff, remains in the organization as Tacoma's pitching coach. Navarro, a former Cubs pitcher, will be entering his sixth season in the Mariners' organization.
Cory Snyder, the hitting instructor at Double-A Jackson the past three years, has been promoted to that same job at Tacoma.
Also staying in the organization is former Rainiers manager Daren Brown, who worked the second half of last year as Seattle's third-base coach. Brown will be a roving instructor overseeing bunting and baserunning in the Minor League system.
Former Mariners catcher and broadcaster Dan Wilson, a member of the Mariners Hall of Fame, will begin his first season as a roving instructor overseeing catchers. Alvin Davis, another Mariners Hall of Famer, continues with his roving instructor role as special assistance coordinator.
Other roving instructors who'll work with all of the Mariners' Minor League squads include field coordinator Jack Howell, pitching coordinator Terry Clark, rehab pitching coordinator Gary Wheelock, hitting coordinator Lee May Jr., infielder coordinator Jim Pankovits, outfield coordinator Brant Brown, Latin America field coordinator Jose Moreno and Latin America pitching coordinator Nasusel Cabrera.
James Horner takes over as the manager at Double-A Jackson, Eddie Menchaca will manage Class A Advanced High Desert and Chris Prieto was named the skipper at Class A Clinton.
Horner managed High Desert last season and will be in his eighth season in the organization. Pitching coach Lance Painter and hitting coach Roy Howell each were part of Horner's High Desert staff in 2013 and will join him in those same roles in Jackson.
Menchaca moves up to High Desert after spending the past three years with Clinton. He enters his sixth seasons in the Mariners' organization, and his teams have reached the playoffs each of the past four years.
Former Clinton pitching coach Andrew Lorraine joins Menchaca in High Desert, while Max Venable has been hired as High Desert's hitting coach in his first year in the organization. Venable, 56, played 12 seasons in the Majors as an outfielder with the Giants, Expos, Reds and Angels.
Prieto takes over the Clinton club after leading Pulaski to the Appalachian Rookie League title in 2013 with a 41-27 record. His staff includes returning pitching coach Cibney Bello, who spent the previous two seasons with the Arizona League Mariners, and returning hitting coach Mike Kinkade.