I have a problem with my pitching style and specially with my speed. Forgive me for the broken English you can read here, it's not my first language (I'm Dominican).
I'm 17 YO but my fastball is pretty "slow", I throw 75-78 but my fastball got two problems: it's somewhat slow and it has a downward movement. I also throw the splitter, cutter, curveball, slide and the screwball (as strikeout pitch, 1 screwball for 20 or more pitches). I can grip the ball like a fastball, do the mechanic correctly and I can't get it like a fastball.
I think that were one of the reasons I was rejected in the tryouts for the team here in the States, I was slow for this age. But I'm more worm killer, not rocket arm. I have completed perfect games over my country mostly with ground outs and strikeouts. They told me something like "you're not in the team because we think you need to work on you arm, the speed and more stuff, come the next year", but I explained I wasn't a rocket arm.
Physically I'm 17, 6'2 and 175. Any advice you can give me. Thanks for your time