Developing proper mechanics then working hard on speeding them up can do wonders. Just for info purposes, when talking about pitching speed for boys, you're undoubtedly referring to baseball. I've been clocking softball pitchers since the 90s. This includes a large number of male softball pitchers from the age of 12 to world class men. I can count on one hand the number of adult male pitchers who threw in the 80-84 mph range. This includes Adam Folkard who threw low 80s at age 18 at a world junior championship. He was way above anyone else in that tournament. American pitchers that I clocked at that tournament were throwing high 60s. This past summer, I have clocked the top u18 boys in Canada and only one of them threw in the low 70s. The rest threw in the 63-68 mph range. I'm now working with a few 14 year old boys who throw high 50s to low 60s. Speeds of 61 to 65 mph at age 15-16 for boys is not exceptional but is considered high level. As for speed increases per year for males, one of my 14 year boys went from 48 to 54 to 63 mph in the last 3 years. The others are first year pitchers so I have no real data on their progress yet. One last note, I'm sometimes amazed at how hard some of these girls can throw at a young age. Also, don't necessarily trust the speed readings on the scoreboard of some of the softball complexes in college ball. Some have speed equipment that seem to be on steroids by 3 to 4 mph for some reason. And no, both of my radar guns are not slow.I know of 15-16 year old boys that are in the 80's with some pushing 90.