A quarter is another way of saying one fourth, in this setting, one fourth of a year = three months. Quarterly means something that happens every 3 months. Edit
Outfielder Ty Cobb, whose career ended in 1928, has the highest batting average in Major League Baseball (MLB) history. He batted .366 over 24 seasons, mostly with the Detroit Tigers. In addition, he won a record 11 batting titles for leading the American League in BA over the course of an entire season.
1. Maury Wills. Maury Wills was a switching-hitting short stop during the glory years of the Los Angeles Dodgers in the late 1950s to middle 1960s, when the team won three world championships. Wills usually batted lead-off and did what he could to get on base, compiling a lifetime batting average of .281 and an on base percentage (OBP) of .330.