Leroux had a 7.00 ERA in 17 appearances with Florida, striking out 18 and walking 11 in 18 innings. He had a 6.28 ERA in 26 minor league games this season.
Leroux was added to the Pirates' 40-man roster.
Bass gave up 11 runs and nine hits in 7 1/3 innings with Pittsburgh. He had a 4.90 ERA in 48 games with Baltimore last season.