There are a couple things that make for pitching success at the amateur level and they are inexorably tied together. Other than the for the few freakizoids who throw the ball absurdly hard, one of them is a pitcher has to be able to throw strikes, and the other is he has to have varying movement on his pitches.
We all know that not throwing strikes will eventually kill a pitcher because it almost always means walks. We all also know that just throwing strikes without movement is really only 1 step above batting practice. So, while they are each important, they do have exist together.
Of course it should go without saying that the varying level of mechanics, control, velocity, attitude, strength, etc., will also affect success. But for the majority of HS kids who climb the hill, if they can throw strikes and vary the movement, they’ll enjoy at least some degree of success.