 Major League Baseball changed its scheduling format beginning in 2001 , further intensifying division matchups throughout the league . The new " unbalanced schedule " allowed for additional games in each season between divisional rivals , replacing additional series with teams outside the division . Due to the change , the Red Sox and Yankees now played each other 17 or more times each season ( 18 times in 2001 ) . The scheduling drew criticism both when it was enacted and after the fact , with some analysts even positing the unbalanced schedule hurt intra @-@ divisional play . 
