It could be good...do you get guys out with it? Do you have more pitches than a 4 seam? It is as important to be able to throw the pitch where you want, can you do that? How much extra are you willing to do to throw harder or better? In high school it isn't just speed. But to answer your question more directly...75 is not bad..you'll need to get better. Work hard, keep up your grades.