Maholm has lost four straight starts and five consecutive decisions, and Pittsburgh is 0-7 in games he started since the All-Star break. Over his past four outings, Maholm's ERA has climbed a half-run to 3.66. He has allowed 17 earned runs and 31 hits in 22 2/3 innings.
The Pirates recalled rookie left-handed reliever Tony Watson from Triple-A Indianapolis on Saturday. Watson was 0-2 with a 2.73 ERA in 25 appearances earlier this season.
Pittsburgh manager Clint Hurdle says he hasn't worked out his upcoming rotation, including a doubleheader on Monday. Brad Lincoln, currently in the bullpen, and Ross Ohlendorf, who began the season in the rotation but is in Indianapolis, are potential options.