This is a baseball term which, depending on context and the speaker, is a type of pitch another pitcher would like to hit, or the exact type of pitch a pitcher should be throwing. The former is usually what is used by offensive minded baseball fans and analysts who see easy pitches to hit as a "pitcher's pitch." The latter is typically used by defensive and pitching minded fans and analysts who see pitching mechanics and style as a way to determine exactly what type of pitch a pitcher should be throwing at any given time.
It should be noted that this is a slang term and has no official meaning or statistic behind it. The differing definitions are most likely the result of the fast, widespread growth of the game. When referring to a pitcher's pitch, they are referring to a pitcher owning said pitch. It is not hard to imagine different people taking that to mean owning the pitch in an offensive way or a defensive way.