ARLINGTON - There are going to be days like this. Texas Rangers top pitching prospect Kumar Rocker did not have his best fastball Thursday. He did not have his best command. What he has, though, seemingly every day is top-shelf composure.

Statcast classifies Kumar Rocker’s nasty breaking pitch as a slider. He calls it a curveball and a “slider at times.” It was the most effective tool in his Texas Rangers debut last Thursday against the Seattle Mariners and secured five of his seven strikeouts.