Batting Average leaders 1903-2012.

Ted Williams led his league in batting average (BA), still referred to as leading the league in hitting by some, six times in three consecutive year couplets:

1941 .406
1942 .356    .050 drop

1947 .343
1948 .369    .026 increase

1957 .388
1958 .328    .060 drop

Williams had big differences in each couplet topped off by a sixty point drop in 1958.  I wondered how unusual that was, not just for an individual, but for any hitters and how much leadership varied between the two major leagues.

Click link to view data and graphs derived from three digit numbers:

http://www.baseball-reference.com/leaders/batting_avg_leagues.shtml

This top ten list is also interesting:

http://www.baseball-reference.com/leaders/batting_avg_top_ten.shtml

Notes:
1. 2013 data is through June 4, 2013.
2. Qualifying rules varied and resulted in anomalies like Debs Garms of Pittsburgh leading NL in 1940  at .355 but with only 385 plate appearances (PA) and 358 at bats (AB); he played in the required 100 games: 103. Now the requirement is 502 PA.  Yes, it should be based on AB but ... baseball and logic often avoid each other.


    AL NL        Ave
min 0.301 0.313 0.318
max 0.420 0.424 0.411
ave 0.356 0.352 0.354

Average is just a straight average of the two leaders in a season, no weighting of (AB).

AL min: Carl Yastrzemski 1968 .301, down .025 from his 1967 triple crown BA .326.
AL max: George Sisler 1922 .420, Ty Cobb 1911 .420.
Name H AB BA
Sisler 246 586 .419795221843003
Cobb 248 591 .419627749576988

NL min: Tony Gwynn 1988 .313
NL max: Rogers Hornsby 1924 .424

Average min: 1968 .318: Yastrzemski .301; Pete Rose .335.
Average max: 1922 .411: Sisler .420, Hornsby .401.



I arbitrarily subtracted the National League (NL) leader from the American League (AL) leader.  Above the zero line, AL leader had the higher BA.  Below the zero line, NL leader had the higher BA.  Based on the three digits, there were virtual ties in 1907, 2000, 2001.

Dif
min -0.069 1905 Elmer Flick .308, Cy Seymour .377 (NL).
max 0.086 1911 Ty Cobb .420, Honus Wagner .334 (NL).



AL NL
min -0.068 -0.057
max 0.057 0.049

The biggest drop was .068: AL Nap Lajoie .376 in 1905, Elmer Flick .308 in 1904 the first year used.

Biggest increase was .057 in 1980: AL Fred Lynn .333 in 1979, George Brett .390 in 1980.

Biggest NL drop was .057 in 1988: Tony Gwynn .313 (lowest all time in NL) from his own .370 in 1987.

Biggest NL increase was .049 in 1920: Edd Roush .321 in 1919, Rogers Hornby .370 in 1920.