I agree with DaleMCM, pitching is going to have to go back in time to get better.
The pitchers in the mlb throw an average 88mph fastball but have got great secondary pitches. They need to go back to hard fastball pitching to bring that average 92-93mph and get more pitchers to throw over 100mph. Now we only have a couple of pitchers that throw that hard when there used to be a lot more of them. Sure its good to see a hard snapping slider or a 3 foot dropping splitter, but its the power of the 100mph fastball that made the game and we need to go back to that.
I believe it starts with the youngest pitchers wanting to learn all the "tricky" pitches at a ridiculously young age, when all that should be doing is throwing a fastball and a changeup. With better coaching at the younger level more players might have a chance of reaching thier full pace instead of having alright junk pitches.
Then we go to high school and college, they need to train on throwing the fastball straight away. Then later introduce the curveball and the slider when thier bodies have gotten mature enough to widthstand the forces on the body with a different pitch, and have gotten used to throwing a hard fastball. Better training and understanding of the body by the coaches might improve the likelyhood of someone throwing 100+mph.
Also the fact that hitters in high school and college use metal bats doesnt help anything. The pitchers have to be able to sneak the pitch passed a hitter, because even if the ball comes off the handle of the bat it might get a safe hit. When with a wood bat if you hit the handle the hitter feels it...bad, and you will most likely get an out. The pitchers need to be more confident in blowing the inside fastball passed the hitter and with a metal bat that wont happen, because once the bat touches that ball its not coming down until its somewhere in the next suburb. Wood bats wood help pitchers in the best of ways, and would help the game in general with everyone being used to the wood bats, hitters would be able to be spotted for more talent instead of hiding behind an aluminium bat.
The game needs its old skool game again, back when a homerun was a challange, with pitchers throwing into the 100+mph range and the speed of the runner was one of the most important things in a game. The game needs to get back to its roots and start fresh and train up kids for speed and power, not tricks.