In 1928, Hartnett hit above .300 for the first time, posting a .302 batting average with 14 home runs. He also surpassed Jack Clements' major league record of 72 career home runs by a catcher. Hartnett also led National League catchers in assists, caught stealing percentage and in fielding percentage. As he matured as a player, he became more disciplined on the field and committed fewer errors. He threw the baseball around the infield in a fearless manner, throwing out baserunners with a high degree of accuracy. Between 1928 and 1938, Hartnett led the league's catchers in fielding percentage seven times.