WAR is a counting stat. It is the number of wins above the "replacement player" you contribute in a season. WAR is incorrectly used as a rate stat: Al Kaline has a career WAR of 92.5 (meaning he single handedly generated 92.5 extra wins for his team), Wade Boggs has a career WAR of 91.1. Some people would claim Boggs contributed less than Kaline, however Boggs was able to generate 91.1 WAR with 856 fewer plate appearances. I would venture to guess Wade Boggs would have been able to generate 1.4 WAR with an extra856 plate appearances (more than one full season).
Here are the WAR/100PA leaders (at least 8,000 PA) (obviously offensive only):
Babe Ruth: 1.535
Mike Trout: 1.343 (added for reference
)
Rogers Hornsby: 1.340
Barry Bonds: 1.288
Mike Schmidt: 1.275
Ted Williams: 1.259
Willie Mays: 1.250
Lou Gehrig: 1.163
Ty Cobb: 1.155
Honus Wagner: 1.115
Tris Speaker: 1.115
Mickey Mantle: 1.107
Eddie Collins: 1.029
Hank Aaron: 1.023
Stan Musial: 1.007
Jimmie Foxx: 1.007
Albert Pujols: .965
Alex Rodriguez: .964
Eddie Mathews: .954
Roberto Clemente: .925
Joe Morgan: .885
Wade Boggs: .848
Rickey Henderson: .830
Cap Anson: .828
Al Kaline: .798
Adrian Beltre: .790
Cal Ripken Jr.: .741
Carl Yastrzemski: .687
Additionally, WAR cannot be used to compare players over multiple eras. There is no stat that does this.
An example:
In 1920, when Babe Ruth played, there were 18.25 million white men between the age of 20-44 and 208 pitchers in the league; so Babe Ruth faced (on average) the best pitcher in a pool of 87,786 people.
In 2010, when Alex Rodriguez played, there were approximately 88.62 million men between the age of 20-44 between the US, Japan, DR, Puerto Rico and Venezuela. There were 635 pitchers in the league; so Alex Rodriguez faced (on average) the best pitcher in a pool of 139,558 people.
If we use 2010 as the point of reference (to compare older players to the players of today) then every stat, including WAR would need to be adjusted 62.9%. So Babe Ruth's 11.9 WAR for 1920, would be adjusted to 7.5 in 2010, which would be tied for 6th with Albert Pujols.
Edited to add: Wins is the most overrated stat. No one really pays attention to saves, the all time career saves leader has never been inducted into the Hall of Fame while holding the title. So, I don't think anyone over rates it.