1928 – The Giants send OF George Harper to the Cardinals for C Bob O’Farrell. O’Farrell, who managed the Birds in 1927, will never regain his effectiveness behind the plate after an arm injury. The trade makes room for 18-year-old Mel Ott to take over the RF position, a spot he will hold for 18 years.

This Day In Baseball

On May 10, 1928 — 1928 – The Giants send OF George Harper to the Cardinals for C Bob O’Farrell. O’Farrell, who managed the Birds in 1927, will never regain his effectiveness behind the plate after an arm injury. The trade makes room for 18-year-old Mel Ott to take over the RF position, a spot he will hold for 18 years.

Source:
Baseball Reference May 10