Back in the early days, there were fewer baseballs to go around. Umpires kept balls in play even after they became tobacco-stained and lopsided. Fans were encouraged to throw foul balls back onto the field--sometimes under threat of arrest. This led to some interesting events on the field.
In an 1891 game between New York and Cincinnati, pitcher Bob Barr--making his Giants' debut that day--was injured in bizarre fashion when he was hit in the head by a ball thrown back over the grandstand by a conscientious fan.
Though no injury resulted, Pirates' third baseman Tommy Leach suffered an embarrassing moment during a 1904 exhibition game. Chasing a pop up behind the bag, he was temporarily blinded by the sun. "I seemed to see two specks of white up above the blinding rays, but I put my hands up as I ran and a few seconds later had the ball in my glove," he explained to a writer from the Cleveland Press. Immediately following the catch, he was surprised to see teammate Honus Wagner standing near third with another ball in his possession. Wagner explained that the ball Leach had caught was a foul thrown back onto the field by a fan. The other had dropped behind third base for a double.