Dogen kept a baseball in his chamber at the Temple. ("What Kate Does") He stated that his son was a baseball fan and that he was killed in a car accident caused by Dogen, though revived by Jacob at the price of Dogen moving to the Island. After a fight with Sayid, Dogen, while in a position to kill him, stops after seeing the ball falling to the floor, probably reminding him of his son, who died because of him. ("Sundown")
Interestingly, there are 108 double stitches on a baseball.