When last seen, the best of the American League's greatest hitters were:
| Adjusted | Nominal | Player | Years in AL | Batting average | % change | # change | ||
| rank* | rank | (all-caps, Hall of Fame; | From | To | Nominal | Adjusted | in BA | in rank |
| * indicates active) | ||||||||
| 1 | 12 | Ichiro Suzuki* | 2001 | 2010 | .331 | .353 | 6.2% | 11 |
| 2 | 1 | TY COBB | 1905 | 1928 | .366 | .353 | -3.9% | -1 |
| 3 | 2 | Shoeless Joe Jackson | 1908 | 1920 | .356 | .351 | -1.3% | -1 |
| 4 | 10 | NAP LAJOIE | 1901 | 1916 | .336 | .333 | -0.9% | 6 |
| 5 | 3 | TRIS SPEAKER | 1907 | 1928 | .345 | .331 | -4.0% | -2 |
| 6 | 16 | ROD CAREW | 1967 | 1985 | .328 | .331 | 0.9% | 10 |
| 7 | 11 | EDDIE COLLINS | 1906 | 1930 | .333 | .326 | -2.2% | 4 |
| 8 | 6 | BABE RUTH | 1914 | 1934 | .343 | .324 | -6.1% | -2 |
| 9 | 8 | LOU GEHRIG | 1923 | 1939 | .340 | .323 | -5.4% | -1 |
| 10 | 18 | JOE DIMAGGIO | 1936 | 1951 | .325 | .322 | -0.7% | 8 |
| 11 | 4 | TED WILLIAMS | 1939 | 1960 | .344 | .319 | -7.9% | -7 |
| 12 | 15 | WADE BOGGS | 1982 | 1999 | .328 | .319 | -2.8% | 3 |
I left the earlier post hanging on the question of how the top hitters would compare when their batting averages were adjusted further, for age. I now have some of the answers.
To get the answers, I quantified the relationship between adjusted batting average and age for the 120 hitters considered in the earlier post. (As a reminder, those hitters attained nominal lifetime averages of .285 or better in at least 5,000 plate appearances in the American League. Their averages take into account long-term and year-to-year changes in playing conditions, as well as differences among ballparks at a give time and over time.) Here is the relationship, in graphical form:
I used the equation shown on the graph to adjust each hitter's annual batting average according to the age at which he attained the average. If the "normal" hitter peaks at 28, as the equation suggests, averages attained before and after the age of 28 are "understated." That is, if a player hits .300 at the age of 20, that's equivalent to hitting .315 at the age of 28; and if a player hits .300 at the age of 40, that's equivalent to hitting .341 at the age of 28.
My analysis of age-adjusted batting average has yielded two key findings, thus far. The first finding, which is captured in the following graph and its accompanying table, is that the top averages for ages 18-41 were accomplished by just seven different players. This graph compares the year-by-year, age-adjusted averages for each of the seven players:
For ease of viewing, I omitted the five players (Speaker, Carew, Collins, Ruth, and Gehrig) who never hold the top spot at any age, despite their impressive career averages. The top hitters at each age are as follows:
| Age-adjusted | ||
| Age | Player | BA |
| 18 | Cobb | .267 |
| 19 | Cobb | .336 |
| 20 | Cobb | .369 |
| 21 | Jackson | .392 |
| 22 | Cobb | .395 |
| 23 | Cobb | .399 |
| 24 | Cobb | .387 |
| 25 | Cobb | .397 |
| 26 | Cobb | .391 |
| 27 | Cobb | .380 |
| 28 | Cobb | .379 |
| 29 | Lajoie | .383 |
| 30 | Cobb | .396 |
| 31 | Cobb | .387 |
| 32 | Cobb | .369 |
| 33 | Suzuki | .377 |
| 34 | DiMaggio | .362 |
| 35 | Lajoie | .414 |
| 36 | Suzuki | .364 |
| 37 | Lajoie | .373 |
| 38 | Williams | .398 |
| 39 | Williams | .343 |
| 40 | Cobb | .357 |
| 41 | Boggs | .343 |
Given that information, it shouldn't surprise you to learn that Ty Cobb returns to the top of the heap when his single-season averages are age-adjusted, and weighted by his at-bats in each season, to obtain an age-adjusted lifetime average. Here is the age-adjusted list of top-12 career batting averages:
| Batter | Age-adjusted career BA | |
| 1 | Ty Cobb | .3639 |
| 2 | Shoeless Joe Jackson | .3559 |
| 3 | Ichiro Suzuki* | .3582 |
| 4 | Nap Lajoie | .3405 |
| 5 | Tris Speaker | .3313 |
| 6 | Rod Carew | .3307 |
| 7 | Ted Williams | .3306 |
| 8 | Eddie Collins | .3258 |
| 9 | Babe Ruth | .3236 |
| 10 | Lou Gehrig | .3228 |
| 11 | Joe DiMaggio | .3223 |
| 12 | Wade Boggs | .3190 |
| * Through 2010 season; before .272 average in 2011 reduced career BA by .0054. | ||
I have not extended my analysis to include the 2011 season, but it is clear that Suzuki now belongs in 3rd place. The loss of .0054 from his nominal career BA in 2011 is far greater than his age-adjusted lead (.0023) over Jackson through 2010.
