Son and I have noticed that young pitchers who are seen as being "lean, wiry, thin-framed, lanky, long-armed, etc" are looked upon more favorably in terms of their projectibility for future success (?read: velocity) Likewise, kids who are "thick-framed, muscular, athletically built, or physically mature" are implied to have already come close to reaching their ceilings in terms of pitching. (read: nothing else to do for the kid, and we can't teach velocity) Is there data to support this? Does everyone buy into this type of thinking? Are recruiters now all thinking this way as well? Don't we have examples in MLB to refute this.
-from the concerned Dad of a muscular boy/man
It's not just pitchers. The more physically mature a kid is perceived to be, the less "projection" will be attached to him. I don't know if it is true in practice, but it intuitively makes sense to me that, just to make up an example on the fly, a 6'2" 160 lbs 17 year old with a large frame who can add 50 lbs of good weight is more likely to add more velocity than a 6'2" 210 lbs 17 year old with a similar frame (i.e., who has already added that 50 lbs) is likely to add. So if they both throw 85 now, it makes sense to me to think that the first kid will likely throw harder than the second kid a few years down the line (assuming the effort levels are equal). Like I said, I don't know if it holds true in practice, but it doesn't seem crazy to me.
Another way of thinking about it is: "research has demonstrated a clear relationship between body mass and pitching velocity" See http://www.gammonsdaily.com/bo...-sabathia-conundrum/ So if that is true, the kid who is likely to gain body mass is more likely to gain velocity. FWIW, the relationship between body weight and velocity was apparently noticed here on HSBBW a number of years ago http://www.community.hsbasebal...peed-and-body-growth (Topic: Interesting Correlation Between Pitching Speed and Body Growth)