I have a sophomore in college that is 5'10" now 182 lost 20 pounds this year on purpose. Sat 86-88 in high school and not sits 86-90 touched 91 this year touched 92 in high school. But has great control of all pitches which include 2 seam, 4 seam, slider, curve, and change-up. He is at a P5 and getting innings as early reliever, middle reliever, closer and situational guy. Has pitched 2 pitches one game to get a guy and 4 pitches another. Has .000 era with 15 innings so far which does not sound like a lot but top guy only has 27 so he is #5 in innings pitched behind the four starters.
I don't think the speed is the key, I think it is the pitchability with LHP's. Can you show a batter 4 pitches in an at bat? The level of play also depends on what you are willing to do as a LHP with 90 or below velo. Are you willing to come out of the bullpen rather than start? I know if he had gone a lower level he would have been starter but he is content with his role right now. Very stressful at times when they bring you in with bases loaded and no outs and say get us out of this but works for some guys. Are you willing to be a guy versus the guy and maybe not throw at all on a weekend or very little according to what the starter does or the other relievers? Just some thoughts. Each player and parent have to decide what they are willing to do to get where they want to get.