SOS:
You seem to bring little Timmy up a lot to describe what 100's, maybe 1,000's of other pitchers can't accomplish. The fact is that he is indeed a "freak" one of a kind pitcher.
I do not know him, but from what I have read Lincecom is actually not a weakling, as you seem to think he is. He is extremely athletic, can do handstands walking around the infield, and other athletic activities that others can't even come close to doing. Some have said he would have been an excellent gymnast. This means to me he is extremely strong in his core, his legs, all with a relatively low weight. Do not equate how much someone weighs to their “strength to weight ratio”.
This site is mostly about HS players, or at least on their way to and from HS ball. The facts are that smaller kids tend to develop their hand eye coordination earlier and their bodies fill out to support their frame earlier. IE core and leg strength. Like most here our experience is with our sons and I can say that my son (who is a college freshmen this year) is still probably a year away from filling out and being capable of supporting his frame properly. I will go dig out a picture from his freshmen year and show you what I mean. There is no way he could have supported his frame with the long and lanky legs he had at that time. So yes stride length has everything to do with do with "strength" or "maturity" or your "core". Arm acceleration maybe not so much.