Interesting thoughts. Actually (volume throwing) is an idea shared by a minority of baseball people.
My first question would be how many times have you thrown the javelin in competition when you were totally fatigued? Not speaking about training, but actual competition.
For instance, pitchers throwing 100 or more pitches trying to win a game, what would be comparable in javelin events? How many javelin throws does it take to place first at an event?
Reason for asking, is I know very little about javelin throwing other than the athlete wants to throw it as far as possible. Not sure how it relates to a baseball pitcher who uses power and deception along with some finesse at times. Most pitchers will have three pitches and they are kind of stressful because there is a hitter in the batters box that wants to hit it harder than you are throwing it.
So other than somewhat the same type throwing motion minus the long run up in javelin I'm not sure we can compare the two. The two major factors in arm injury involve fatigue and recovery time. Still an interesting theory though.
BTW, congratulations on such an outstanding career. Very amazing!