Was reading and article about speed differential btw #1 and #2. It says that 5% to 12% differential is ideal. Is it me does 5% sound low, 3.5 mph diff on a 70 mph fastball? From my experience, 10% differential would be ideal

Why not just think of pitch speed in terms of mph?

In my experience, a good change up is usually 12 to 15 mph off the FB for high school pitchers and above. A good breaking ball is generally 10 to 12 mph off the FB. What's tough about these generalities, though, is that everyone's different, particularly with their breaking balls.

The key more than speed, in my opinion, is deception, movement and command. In other words, do you have the confidence in your stuff to throw an off-speed pitch with the bases loaded and a full-count on the batter, if that's what the situation dictates?

Not much to add to Steve's post. I have always used 10MPH as a rule of thumb for HS. If you can get to 12-15 with FB deception (arm speed) you will be very difficult.

I think Ellis pegged it correctly. Yes, there are general arbitrary goals for pitch speeds. And they are typically what's been listed already. However, all pitcher's shouldn't be forced to fit into arbitrary guidelines.

If a pitcher's changeup is only 8mph off the FB but he drops it off a table and can locate it then leave him alone. Of course, there's always stuff to work on and improve but don't overhaul this type of kid's changeup because his numbers don't fit the mold. Same thing for other pitches as well.

I think you'll find that most MLB changeups have less than a 10 mph differential. If you check the gameday pitch velocities the typical differential is about 6 to 7 mph for most MLB pitchers.

Pitching coaches probably cause a lot of problems if they try to get young pitchers to come up with more of a differential than they need to be successful.