Nunez signed a minor-league contract with the Guardians on Tuesday that includes an invitation to spring training.
Nunez signed a minor-league contract with the Pirates on Tuesday.
Nunez signed a minor-league contract with the Cubs on Monday.
Nunez was designated for assignment by the Giants on Tuesday.
Nunez was claimed off waivers by the Giants on Wednesday.
Nunez was optioned to Triple-A Albuquerque on Sunday.
Nunez was recalled from Triple-A Albuquerque on Friday.
Manager Bud Black confirmed Sunday that Nunez will make the Rockies' Opening Day roster as the team's backup catcher, Thomas Harding of MLB.com reports.
Nunez went 1-for-4 with a solo home run in Saturday's 11-2 loss to the Diamondbacks.
Nunez hit a solo home run as a pinch hitter in Friday's 9-7 win over the Diamondbacks.