In a 10 – 4 loss to Texas, Luis Tiant hits and flies out. He is the first Boston pitcher to hit since the designated hitter was put into effect in 1973.

On July 12, 1975In a 10 – 4 loss to Texas, Luis Tiant hits and flies out. He is the first Boston pitcher to hit since the designated hitter was put into effect in 1973.

Source
Baseball Reference July 12