Gonzalez's finger has recently become so swollen that he struggles to hold on to the bat. He's hitting only .255 this season.
To take Gonzalez's place on the roster, the Rockies recalled infielder
Peterson batted .174 in 10 games, including seven starts, in his first stint with the Padres.
Hahn lasted 2 2-3 innings in his major league debut in a 4-1 loss to Pittsburgh on Tuesday night.