I liked the way it went with the older MLB 2K games. You could put team resources into coaches, and one of the options for pitching coaches was to teach pitchers new pitches. I remember with, like, 2K6 or 2K7, Jake Peavy learned a forkball that was totally ridiculous. It was really slow and literally had drop that could have it start at the top of the strike zone, then end in the dirt. The pitch was basically useless because of the obscene break, but it was funny.