Barrett, 27, was designated for assignment for the second time in a month on Feb. 22. He was traded to the Giants for cash considerations after being DFA’d by the Diamondbacks on Jan. 31.
Barrett had an intriguing rookie season out of Arizona’s bullpen in 2016, recording 8.5 K/9 and a 3.49 ERA, but a shoulder injury derailed his 2017 season. He looked good at times in AAA last season, finishing with a 2.87 ERA and 11.3 K/9, but he also had a 3.71 FIP and averaged 4.9 walks per nine. The Diamondbacks brought him back to the majors in September, where he allowed four runs in seven innings.