Single Season Leaders for Isolated Power

Isolated Power is a SABERmetric statistic that attempts to describe a hitter's overall effectiveness by measuring his ability to generate extra base hits. Isolated Power was created by baseball great Branch Rickey along with Allan Roth during the 1950's and they termed it Power Average. Isolated Power is calculated by substracting batting average from slugging percentage.

Important notes: 1,000 career games played are needed to make this list, raw averages are presented to further clarify the one-hundred greatest career isolated power averages of all-time, and a bold faced entry denotes that the player was active during the previous Major League season.
"My relationship (with the San Francisco Giants) has been up and down, but for the most part has been good. This year it's been exceptionally good. You walk into a store, and you run into little old ladies who've never seen a baseball game before in their whole life, telling you what a great accomplishment you have." - Barry Bonds on ESPN.com (Bonds finishes remarkable season with 73, 10/07/2001)
Isolated Power
Single Season Leaders

'Top 100'
Barry Bonds .536 (.53571) 2001 San Francisco Giants NL 1
Babe Ruth .472 (.47162) 1920 New York Yankees AL 2
Babe Ruth .469 (.46852) 1921 New York Yankees AL 3
Mark McGwire .454 (.45383) 1998 St. Louis Cardinals NL 4
Barry Bonds .450 (.45040) 2004 San Francisco Giants NL 5
Barry Bonds .429 (.42928) 2002 San Francisco Giants NL 6
Mark McGwire .418 (.41844) 1996 Oakland Athletics AL 7
Mark McGwire .418 (.41843) 1999 St. Louis Cardinals NL 8
Babe Ruth .417 (.41667) 1927 New York Yankees AL 9
Mark McGwire .410 (.41009) 1995 Oakland Athletics AL 10
Sammy Sosa .409 (.40901) 2001 Chicago Cubs NL 11
Barry Bonds .408 (.40769) 2003 San Francisco Giants NL 12
Lou Gehrig .392 (.39212) 1927 New York Yankees AL 13
Babe Ruth .386 (.38619) 1928 New York Yankees AL 14
Jimmie Foxx .385 (.38462) 1932 Philadelphia Athletics AL 15
Jeff Bagwell .383 (.38250) 1994 Houston Astros NL 16
Barry Bonds .381 (.38125) 2000 San Francisco Giants NL 17
Frank Thomas .376 (.37594) 1994 Chicago White Sox AL 18
Albert Belle .374 (.37363) 1995 Cleveland Indians AL 19
Jim Thome .373 (.37292) 2002 Cleveland Indians AL 20
Babe Ruth .373 (.37259) 1930 New York Yankees AL 21
Mark McGwire .372 (.37222) 1997 Oakland Athletics AL 22
St. Louis Cardinals NL
Babe Ruth .372 (.37165) 1923 New York Yankees AL 23
Mickey Mantle .370 (.36965) 1961 New York Yankees AL 24
Hank Greenberg .369 (.36871) 1938 Detroit Tigers AL 25
Hack Wilson .368 (.36752) 1930 Chicago Cubs NL 26
Babe Ruth .366 (.36566) 1926 New York Yankees AL 27
Luis Gonzalez .363 (.36289) 2001 Arizona Diamondbacks NL 28
Babe Ruth .361 (.36106) 1924 New York Yankees AL 29
Javy Lopez .359 (.35886) 2003 Atlanta Braves NL 30
Babe Ruth .357 (.35714) 1922 New York Yankees AL 31
Albert Belle .357 (.35680) 1994 Cleveland Indians AL 32
Jimmie Foxx .356 (.35575) 1938 Boston Red Sox AL 33
Barry Bonds .355 (.35493) 1999 San Francisco Giants NL 34
Larry Walker .354 (.35387) 1997 Colorado Rockies NL 35
Rogers Hornsby .353 (.35317) 1925 St. Louis Cardinals NL 36
Mickey Mantle .353 (.35272) 1956 New York Yankees AL 37
Babe Ruth .353 (.35271) 1929 New York Yankees AL 38
Ken Griffey, Jr. .351 (.35104) 1994 Seattle Mariners AL 39
Roger Maris .351 (.35085) 1961 New York Yankees AL 40
Travis Hafner .350 (.35022) 2006 Cleveland Indians AL 41
David Ortiz .349 (.34946) 2006 Boston Red Sox AL 42
Todd Helton .349 (.34923) 2001 Colorado Rockies NL 43
Ralph Kiner .348 (.34791) 1949 Pittsburgh Pirates NL 44
Jimmie Foxx .347 (.34729) 1933 Philadelphia Athletics AL 45
Sammy Sosa .347 (.34720) 1999 Chicago Cubs NL 46
Willie Stargell .347 (.34674) 1973 Pittsburgh Pirates NL 47
Manny Ramirez .346 (.34624) 2000 Cleveland Indians AL 48
Ryan Howard .346 (.34596) 2006 Philadelphia Phillies NL 49
Carlos Pena .345 (.34490) 2007 Tampa Bay Devil Rays AL 50
Kevin Mitchell .344 (.34438) 1989 San Francisco Giants NL 51
Rudy York .344 (.34400) 1937 Detroit Tigers AL 52
Lou Gehrig .344 (.34370) 1934 New York Yankees AL 53
Jim Gentile .344 (.34362) 1961 Baltimore Orioles AL 54
Ted Williams .343 (.34286) 1957 Boston Red Sox AL 55
Lou Gehrig .343 (.34251) 1930 New York Yankees AL 56
Jim Edmonds .342 (.34228) 2003 St. Louis Cardinals NL 57
Ken Griffey, Jr. .342 (.34211) 1997 Seattle Mariners AL 58
Lou Gehrig .342 (.34197) 1936 New York Yankees AL 59
Hank Aaron .342 (.34184) 1973 Atlanta Braves NL 60
Hank Aaron .341 (.34141) 1971 Atlanta Braves NL 61
Barry Bonds .341 (.34137) 1993 San Francisco Giants NL 62
Jim Edmonds .341 (.34137) 2004 St. Louis Cardinals NL  
Brady Anderson .340 (.34024) 1996 Baltimore Orioles AL 64
Albert Pujols .340 (.34019) 2006 St. Louis Cardinals NL 65
Willie Mays .340 (.33966) 1955 New York Giants NL 66
Matt Williams .339 (.33933) 1994 San Francisco Giants NL 67
Sammy Sosa .339 (.33904) 1998 Chicago Cubs NL 68
Mike Schmidt .338 (.33759) 1980 Philadelphia Phillies NL 69
Willie McCovey .336 (.33605) 1969 San Francisco Giants NL 70
Babe Ruth .336 (.33565) 1919 Boston Red Sox AL 71
Barry Bonds .335 (.33504) 1994 San Francisco Giants NL 72
Jimmie Foxx .334 (.33405) 1939 Boston Red Sox AL 73
Reggie Jackson .333 (.33333) 1969 Oakland Athletics AL 74
Jim Thome .333 (.33270) 2001 Cleveland Indians AL 75
Willie Stargell .333 (.33268) 1971 Pittsburgh Pirates NL 76
Tony Clark .332 (.33238) 2005 Arizona Diamondbacks NL 77
Hank Greenberg .332 (.33165) 1937 Detroit Tigers AL 78
Larry Walker .331 (.33105) 1999 Colorado Rockies NL 79
Alex Rodriguez .331 (.33105) 2007 New York Yankees AL  
Prince Fielder .330 (.32984) 2007 Milwaukee Brewers NL 81
Hank Greenberg .330 (.32984) 1940 Detroit Tigers AL  
Manny Ramirez .330 (.32950) 1999 Cleveland Indians AL 83
Ted Williams .329 (.32903) 1960 Boston Red Sox AL 84
Juan Gonzalez .329 (.32902) 1996 Texas Rangers AL 85
Ted Williams .329 (.32895) 1941 Boston Red Sox AL 86
Mark McGwire .329 (.32855) 1987 Oakland Athletics AL 87
Willie Mays .328 (.32796) 1965 San Francisco Giants NL 88
Babe Ruth .328 (.32772) 1931 New York Yankees AL 89
Mike Schmidt .328 (.32768) 1981 Philadelphia Phillies NL 90
Ken Griffey, Jr. .327 (.32701) 1998 Seattle Mariners AL 91
Hank Greenberg .327 (.32696) 1946 Detroit Tigers AL 92
Joe DiMaggio .327 (.32689) 1937 New York Yankees AL 93
Albert Belle .327 (.32677) 1998 Chicago White Sox AL 94
Al Simmons .327 (.32671) 1930 Philadelphia Athletics AL 95
Derrek Lee .327 (.32660) 2005 Chicago Cubs NL 96
Albert Pujols .326 (.32601) 2004 St. Louis Cardinals NL 97
Todd Helton .326 (.32586) 2000 Colorado Rockies NL 98
Stan Musial .326 (.32570) 1948 St. Louis Cardinals NL 99
Ralph Kiner .326 (.32566) 1947 Pittsburgh Pirates NL 100
Current Through End of 2007 Regular Season


Why is the Isolated Power statistic not used commonly? Should it be used more often? Is it better than on base plus slugging? Share your opinion on Baseball Fever where we have an entire forum dedicated to advanced statistics.

The American League single season record for isolated power was set in 1920 by Babe Ruth of the New York Yankees. The National League single season record for isolated power was set in 2001 by Barry Bonds of the San Francisco Giants.

Bonds, McGwire and Ruth are the only three (3) players in Major League history with a career isolated power mark greater than .299, but which one of these single season isolated power dominators is the career leader for isolated power?
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