What Kind of Pitching Prospects Work out the Best?

There isn't much need for a real introduction here, but I wanted to continue my look at the correlation between velocity and success. Here, we will look at prospects using Baseball America. I think this gets rid of some of the selection bias that might have happened in my previous post on ZIPs and velocity when it came to prospects, as we do get to look at pitchers that failed to make the Majors.

I looked at pitchers from 2005-2009 (I think there are a few missing from 2007 because of website setup, but it is still 130 pitchers each) Baseball America's organization rankings. Before 2005, Baseball America did their organizational rankings a little differently, so I couldn't really go back further than that (and stopping at 2009 gives the prospects at least some time to make the Majors). I didn't care about the actual rankings for this, I just looked at the pitchers that were identified as having either the best fastball, curveball, slider, changeup, or control. There were obvious repeats, whether yearly or being the best at more than 1, but I decided to keep those in and rate them as the same. If you want to look at my actual spreadsheet, you can here, but the most important part is below where the results of the pitchers MLB FIP - and WAA are grouped:

Best Fastballs: 110 out of 130 made the Majors. They had an average FIP - of 111.39 and average WAA of .99.

Best Curves: 93 out of 130 made the Majors. They had an average FIP - of
105.77 and average WAA of 1.91.

Best Sliders: 101 out of 130 made the Majors. They had an average FIP - of 109.06 and average WAA of .31.

Best Changes: 87 out of 130 made the Majors. They had an average FIP - of 118.61 and average WAA of -.11

Best Control Pitchers: 90 out of 130 made the Majors. They had an average FIP - of 117.96 and average WAA of .42

So out of the players that Baseball America recognized as having the best fastballs or the best control in the organization, the fastball pitchers not only made the Majors more, they were more successful in the Majors. The fastball pitchers made the majors more than any of the other pitchers, with the changeups having the least. The changeup pitchers that did make the Majors were also the worst. However, you notice that the fastball pitchers were not the most successful in the Majors. The curveball pitchers were. One reason for this could be that pitchers with elite fastballs were given chances in the Majors, even though perhaps they didn't deserve it (numbers wise or breaking pitches wise), just because of their fastballs. That is, there could be a selection bias because teams value fastball velocity so much (which is one of the reasons I added two different measures of effectiveness along with just the number of pitchers that made the Majors). We have also seen that pitchers without real curveballs tend to be less successful than pitchers that do have curveballs. It is an old baseball saying that curveballs often separate the sheep from the goats for both pitchers and hitters, and perhaps this data shows that their is certainly something to that. I have looked at curveballs in the past, but perhaps we should be looking at them more when looking at pitching prospects, along with fastball velocity.