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Batters need to input X number of pitches, so that they can recognize spin in the first 10-20 feet ... with X going up or down per talent level.
X seems to equal about 5,000-8,000 or so pro pitches, as a rule of thumb, for the average guy.
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Pitchers don't need the info-jack. They're working on their own sports movements without much regard to what's happening around them.
How long does it take for a bowler to crack a 200 average? There's no set amount of time. "Career Arc" is fundamentally a construct for hitters.
Many historical pitchers were very good at age 19. Such as Felix. Tim Lincecum could have stepped off the UW diamond over to Safeco and thrown a shutout in the majors.
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