Mickey Mantle: League BA 1951-1968

Mickey Mantle's batting average (BA) dropped from .365 in 1957 to .237 in 1968.  The previous post addressed the percent above league average, defined in baseball-reference.com as "a league average (non-pitcher) would have had in the same park(s)" for Mantle, Willie Mays and Hank Aaron for BA, OBA, SLG, OPS.

I wondered if  baseball-reference.com simply listed an unweighted average for lgBA for a player's seasons of if the lgBA was weighted by the proportion of at bats (AB) or plate appearances (PA) of that player's career.  I checked it for Mantle and at least for the lgBA for his seasons, 1951-1968, the lgBA is either weighted or coincidentally correct: .256.  Mantle's career BA was .298, 16.41% above lgBA.

Click link and tab "AL BA" to view detailed data and graph.

lgBA was as high as .265 in 1953 and 1955 but by 1968 was down to .232.

Year lgBA
1951 0.263
1952 0.253
1953 0.265
1954 0.262
1955 0.265
1956 0.264
1957 0.262
1958 0.257
1959 0.256
1960 0.258
1961 0.258
1962 0.261
1963 0.254
1964 0.258
1965 0.250
1966 0.242
1967 0.238
1968 0.232
BB-Ref 0.256