We don’t know where Josh Hamilton will end up in terms of career WAR, but after the jump you can see where the other guys who hit four homers in a game ended up.
Willie Mays 151.3
Lou Gehrig 107.1
Mike Schmidt 99.9
Mike Cameron 42.8
Rocky Colavito 41.9
Gil Hodges 41.0
Carlos Delgado 40.5
Chuck Klein 39.9
Shawn Green 30.9
Joe Adcock 29.6
Bob Horner 19.4
Mark Whiten 12.3
Pat Seerey 3.0
The WAR numbers are b-ref’s latest version. There’s a bit of a logjam on this list around 40 WAR. Josh Hamilton, mid-career but not having started his major league career until 26 as a result of his personal issues, is at 21.8 WAR.
As noted in the comments, I’ve left out of the list above the two 19th century four-homer-in-a-game guys:
Ed Delahanty: 66.2 WAR when he died while still active at 35, after a mental breakdown and the infamous fall or jump from a railroad bridge near Niagara Falls. Two of Big Ed’s homers on his four-homer day were inside-the-park jobs.
Bobby Lowe: 17.2 WAR, he had a long, solid career as a second baseman, not a slugger. A.D. Suehsdorf writes at BaseballLibrary.com of Lowe’s four-homer day that “The home runs came consecutively, in six at-bats, all over the 250-foot left-field wall of Boston’s Congress Street Grounds, the Beaneaters’ temporary home while their regular park was under repair.” http://www.baseballlibrary.com/ballplayers/player.php?name=bobby_lowe_1868
