Ted Williams is best known for batting .406. What is not nearly as well known is that he had a lifetime slugging average exceeded only by Babe Ruth's -- and Williams' lifetime batting average of .344 was two points higher than the Babe's. So no one had both a higher lifetime batting average and a higher lifetime slugging average than Ted Williams. He too makes the short list.
There is another important dimension to batting, the ability to come through in the clutch. This is not so easily quantifiable. However, there is one batter who stands out above all others when it comes to runs batted in -- Lou Gehrig.
Despite a career shortened by the disease that bears his name, Lou Gehrig still holds the record for the most seasons with more than 150 runs batted in -- seven seasons, one out of every two full seasons in his career. Babe Ruth is second with three seasons of 150 or more runs batted in. Gehrig had 184 RBIs in 1931.
Lou Gehrig also set the lifetime record for the most home runs with the bases loaded, a record recently tied by Alex Rodriguez. Babe Ruth, Hank Aaron and Barry Bonds, in their longer careers, hit over 200 more home runs than Gehrig, but none of the three hit as many homers with the bases loaded.
Lou Gehrig's lifetime slugging average is third on the all-time list, just one point behind Ted Williams'. Gehrig's lifetime batting average of .340 is 2 points lower than Babe Ruth's and 4 points lower than Ted Williams'. But, if clutch hitting counts, Gehrig also belongs on the short list of all-time great batters.
We can argue about how to weigh various aspects of hitting, in order to pick the one all-time greatest batter, but at least we can narrow down the list of possibilities to five.