The Chicago White Sox have called up top pitching prospect Aaron Poreda to Chicago from Double-A Birmingham. No corresponding move has been announced.

Poreda could be coming to the majors for a variety of reasons, but he could either replace Clayton Richard or Bartolo Colon in the rotation, with fellow starting pitcher Jose Contreras doing the same – or he could be sliding into long relief. The White Sox have not yet announced the move, so no one has been moved off the 25-man roster yet.

Poreda, 22, was the top pitching prospect in the Sox system according to FutureSox. The 6-6 lefty has  been impressive in Birmingham, going 5-4 with a 2.38 ERA. He’s struck out 69 in 64.1 innings, but has also walked 35 in that same time span. Southern League batters are hitting just .206 against Poreda.

The burly lefty features high 90s gas, but has been working in the minor leagues to refine his breaking pitches.