I am a Mets fan and watch 4-5 games a week. Whenever I watch MLB I marvel at the effectiveness of the changeup. In softball the changeup does not seem as effective. Maybe that's just a subjective judgement and has no basis in fact and I'm open to other opinions. One thing is clear when comparing the MLB changeup to what I see in softball, there is a significant difference in velocity when compared to a fastball. A quick foray on Baseball Savant shows that changeups are used roughly 20% of the time but that varies significantly from 5% to 30% pitcher by pitcher. The velocity difference is a lot more consistent, it is roughly 10mph or about 10-15% less than the fastball. In softball changeups are usually about 15-20mph slower, or 20-30% less than a fastball. My numbers are quick generalizations and there might be some hard research that will prove them wrong. But if they do hold up the question is does the velocity difference in softball make the pitch less effective or more vulnerable to getting hit hard. Does the velocity difference make it easier to detect so that hitters are not fooled by it?