Complex sentence: His batting average rose to a.306 in 1931 making him one of the best hitting catchers in the American League and, although he led the league's catchers in errors and passed balls, he also led the league in assists.
Split into simpler sentences: His batting average rose to.306 in 1931, making him one of the best hitting catchers in the American League. Although he led the league's catchers in errors and passed balls, he also led the league in assists.