My WAR calculation is a combination of Baseball-reference and Clay Davenport; I believe it to be the "best" WAR number available for historical comparison. 8 WAR is an MVP quality season. The record is pythagorean adjusted for 162 games.
1964 89-73
C Tom Haller 3.1
1B Orlando Cepeda 4.3
2B Hal Lanier 1.85
SS Jose Pagan -1.3
3B Jim Ray Hart 5.2
LF Willie McCovey .2
CF Willie Mays 10.95
RF Jesus Alou -.05
OF Harvey Kuenn -.6
IF Jim Davenport 1
OF Matty Alou .25
IF Chuck Hiller -.35
C Del Crandall .65
OF Duke Snider -.6
SP Juan Marichal 6.2
SP Bobby Bolin 2.5
SP Bob Hendley 1.85
SP Rob Herbel 1.9
SP Jack Sanford 1.7
SP Gaylord Perry 5.05
RP Jim Duffalo 1.4
-Mays goes over 10 WAR for the third straight season; this is now his best yet, the second best Giants season ever. And - he passes Mathewson in career WAR. Masanori Murakami becomes the first Japanese player in MLB history.