Sanchez, 28, hit .202 with three home runs and 17 RBI in 55 games with the Marlins this season before being demoted to Triple-A New Orleans.
In 2011, Sanchez was an All-Star and finished the season with a .266 average, 19 homers, 35 doubles and 78 RBI.
Kaminska, 23, went a combined 6-4 with a 5.20 earned run average in 33 relief appearances this year between New Orleans and Double-A Jacksonville.
The 24-year-old Hernandez appeared in 25 games with the Pirates this season and picked up two hits in 24 official at-bats. In 67 games with Triple-A Indianapolis, Hernandez hit .257 with two homers and 13 stolen bases.