Another thought on the mindset of combining FB-Velo with the ACT score (or a converted SAT to ACT score), is it forces the player to realize that even though he may have an 88mph FB as a sophomore, or even as a Junior, that he may be closing doors on himself if that's the only number he focuses on? That the ACT# and the SAT# are equally important data points for many colleges, especially HA ones. That they should go hand in hand as far as getting noticed, or getting your foot in the door, or beginning the conversation with a HA.
"Hey RHP-son, you may have an 88-FB, but your 22-ACT score gives you a grand total of #110 points." If kid can see that the goal is "120" for HA, not just 88, 89, or 90 (for an RHP for example), he may then be inspired to hit the test books as hard as the weighted balls, or he may just decide it's time to take his 88-FB to Mid-Major State U instead.
Again, as has been previously mentioned on this thread, the earlier that a viable ACT/SAT test number can be plugged in the equation? The better.