Hey just wanted to weigh in here. My sophomore year of high school I was throwing low 70’s with what I deemed as solid mechanics and a good work ethic. What I came to realize as I went through high school is that I had no idea how much improvement I had in me. I’m in college now throwing mid to upper 80’s simply because I sat down, realized I didn’t know everything, and used the resources around me to improve. Pitching isn’t a race, or a marathon, or anything of the sort because there is no end to it. You may be a bit behind the “average” or “above average” right now, but in a year or two that won’t mean diddly squat. Get in touch with someone to help you work that has been there, be it a coach, older player, or someone knowledgable in baseball, and work with them to find a way to do it. I can tell you that personally, if you want to throw harder, you have to try and throw harder, if that sounds simple enough. Long toss with INTENT. Your arm will not get stronger if you don’t push it. Give it adequate rest but when you throw then THROW. I guess I’m getting into this one because I’ve been in a similar situation, but don’t worry about where you are now, because down the road it will not matter. Right now you need to focus on yourself and no one else. Do the research, get yourself a lifting program that’s pitching specific, because gaining fifteen pounds of muscle isn’t going to help if it’s not the right kind of muscle, or if you lose flexibility over it. To summarize, throw with intent, do your homework, and find someone you can trust to work with on this, because outside help makes it all easier. Good luck.