As high school coaches, we have always strived to teach pitchers the right way to pitch, physically and mentally.
Physically means making sure pitchers use the correct grips, are taught mechanics that best fit their body type, and are prepared to play by having drills and programs to improve performance.
The mental aspect is about teaching to throw to the 4 quadrants, learning and using different pitches, changing speeds, pitching quickly and acquiring poise and mental toughness in game situations.
Where this gets blurred is when a team faces a pitcher who throws to one spot using one pitch and is successful. How does a coach explain to his players that that won't work over a long period of time?
I have come across that scenario several times and I have told my teams that they could also do it that way if we find out that a team cannot hit a particular pitch or location. Because we practice using every pitch in every location, we are prepared for that scenario.
When teams practice throwing to one location or rely on throwing just one pitch, it is a recipe for losing baseball. Diversification is a proven method to controlling hitters because they start to guess pitch and location. When hitters start to think, they slow their bats down, leading to easy outs and wins.
This is pitching, not throwing.