I agree that nobody can say for certain that Mark Prior's drastically reduced effectiveness after 2003 was directly caused by Dusty Baker (or his pitching coaches Larry Rothschild and Dick Pole) overworking him in 2003. It is impossible to prove that. I agree there were other contributing factors as well. I have not been one of the people who blame Dusty Baker for ruining Mark Prior (I expressed that clearly in posts #73 and 86 in this thread). But I also realize that Prior was indeed overworked in 2003 and I would strongly caution any manager from handling a pitcher in that manner. We simply know better these days. We now know that handling a pitcher in that manner is very likely (but not certain) to lead to reduced effectiveness and greatly increases the odds of getting hurt.
My point is merely that we know with 100% certainty that overworked pitchers are much more likely to get hurt and they are much more likely to experience drastic performance declines. By the way, overwork can be a matter of too many innings in a season, too many pitches in a game, or not enough time to recuperate between outings.
I agree with you 100% that not all pitchers who are overworked are going to get hurt or suffer drastic performance declines -- but they do at a much higher rate than non-overworked pitchers.
I agree with you 100% that not all pitchers who got hurt did so because of overwork -- pitching is dangerous even when handled carefully. Perhaps they would have broken down even earlier if they hadn't been babied.
Some smokers live to old age. Some non-smokers get lung cancer anyway. We can't say for certain how many cigarettes it takes to kill you. Some people can safely smoke more than others. But we still know that smoking is very dangerous to your health.
Some overworked pitchers don't get hurt. Some babied pitchers get hurt anyway. We can't say for certain how many pitches it takes to ruin you. Some pitchers can safely throw more than others. But we still know that pitching too much is very dangerous to your health.