Contreras allowed just one run in seven innings during Double-A Altoona's win over Erie on Tuesday. He allowed two hits and one walk while striking out 10.
The right-hander has compiled a 2.03 ERA, 0.80 WHIP and 57:9 K:BB in 40 Double-A innings, keeping opponents scoreless in four of his seven starts. Contreras, who came to Pittsburgh as part of the Jameson Taillion trade, has a chance to move to Triple-A before summer's end.