I don't know who came up with the info on this chart but it seems to have been pulled out of the air. I took a look at 4 Division 1 rosters. Just the first 4 schools that came to mind.
There were 8-10 girls on each roster at 5'6" or less. The shortest girl I saw was 4'10" and a couple of others at 5'2". On these 4 rosters there were a total of 4 pitchers at 5'6" or less.
I don't follow college softball as much as some do but I think I looked at 4 schools that have some credibility. University of Michigan, University of Alabama, University of Arizona and Arizona State have some decent programs and are probably indicative of what is going on at higher levels of college softball.
Good job China covering for our laziness! My point exactly. And I would say this was typical of the teams I coached.