I'd never heard of him, so here's the press release...
TWINS NAME GARVIN ALSTON PITCHING COACH
Minneapolis/St. Paul, MN – The Minnesota Twins announced today that they have named Garvin Alston as Pitching Coach.Alston becomes the 16th pitching coach in club history and fourth since 1985.
Alston, 45, most recently served as Major League Bullpen Coach for the Oakland Athletics after beginning the 2017 season as Pitching Rehab Coordinator for the San Diego Padres.The 2018 season will mark Alston’s 14th as a coach in some capacity at the professional level. He previously served as the Arizona Diamondbacks’ Major League Bullpen Coach in 2016, Minor League Pitching Coordinator for Oakland in 2015, Minor League Rehab Pitching Coordinator for Oakland from 2009-14, and Oakland’s Single-A Pitching Coach in Stockton (2007-08) and Kane County (2005-06).
The Mount Vernon, New York native was selected by the Rockies in the 10th round of the 1992 First-Year Player Draft out of Florida International University in Miami, Florida.The former right-handed pitcher played nine seasons of professional baseball in the Colorado Rockies, Kansas City Royals and Los Angeles Dodgers organizations, including six appearances in the major leagues with the Rockies in 1996.