When Ted Williams hit .406 in 1941 he became the first player since 1930 to do so. 67 years later, an 11 year gap between .400 hitters seems minimal. Between 1901 and 1941 the majors saw 13 .400 or better batting averages. None since. Chipper Jones made a run this season, but turned up well shy at the end. Tony Gwynn fell three hits shy in 1994. Heck, the last time we even had someone end the season with a batting average over .370 was 2004, Ichiro finished the season at .372 while breaking George Sissler's single season hits record. Why has it been so long since baseball's last .400 hitter?
Defensive Evolution
Baseball's came a long way since the 40's, nowadays they even let the defense have nine fielders. Seriously though, if the 2008 Washington Nationals played a game against the 1927 New York Yankees at a neutral park without a designated hitter, who do you think wins eight out of ten times? Simply put, baseball players of today's game are far superior to their sepia toned brethren. Apply the athleticism gains to the defensive team and you're likely to see less bloopers dropping, more fantastic seeing eye singles robbed, and more over the shoulder warning track grabs in one season than some fans in the 1920's saw their entire lives. That's not to mention the pitchers, although we'll get to them in depth in a few moments. They no longer record over 1,000 outs during any given season, but they throw harder, more accurately, and have modern medicine on their side for every ache and pain.
Ballparks
Perhaps the most glaring change is the location of the fences. Now further in to accommodate for more stands. Even when teams do build cavernous homes they usually give in to their peeved hitters demands. Particularly those who have raises resting upon their homerun totals. Chock this up as another point in defensive evolution; if there's less ground to cover, what becomes more important for fielders: quick acceleration or sustainable speed? When paired with routes and ball-reading abilities, the words "quick first step" are usually death to line drives, while "slow, but steady" are left for childrens' tales.
Strikeouts
During Ted Williams' 1941 season he struck out 27 times in 143 games. Jack Cust struck out 27 times in his team's first 24 games this season. It's not that today's players aren't able to maintain batting averages on balls in play over .400, unnecessary to hit .400 anyway, but instead they aren't able to sustain the batting average itself. To illustrate my point, in 1977 Rod Carew finished with a BABIP of .408.By all means that would be enough to guarantee a .400 batting average, but every time Carew struck out, 55 in total, he would damage not his BABIP, but solely his BA. Carew's 14 homeruns also left his BABIP unaffected while adding to his BA. The added luck isn't the issue, however the amount of balls in play are down, meaning a .400 BABIP isn't what it used to be, before the strikeout became the norm.
Prospects
Heading forward, will we ever see another .400 hitter? Almost certainly. Despite 2008 featuring only a single player with more than 500 (Note: Jones finished with 439) at-bats and a batting average over .350 there are a few players that could definitely pull it off. Particularly that one player, he goes by the name Albert Pujols. A rare breed, Pujols hits 35-plus homeruns on a yearly basis, and has the potential of hitting upwards of 50. Unlike most of the homerun trotters Pujols is not going to strike out 100 plus times. In fact, Pujols hasn't struck out more than 60 times since 2005. Combining a lack of strikeouts with a surplus of homeruns creates part of the perfect storm necessary to record hits in 40% of a player's at-bats.
The question of course is, if Pujols is such a good candidate why hasn't he hit over .360 yet? Pujols is going to record around 190 hits in any given season, 35 of those will be homeruns, which explains part of the reason why he's yet to have a BABIP inflated season towards the realm of .400. As previously mentioned, a .400+ BABIP is not necessary to possess a .400 batting average if a player can maintain a good homerun rate and fend off enough strikeouts. So what does all of this mean? Well, Pujols simply needs his prime years to come through with one magical season in order to put this talk behind us.
As for some other candidates...
Ichiro Suzuki: He's had the BABIP (over .390 in 2004, and nearly .390 in 2007) unfortunately he doesn't have the homeruns or strikeout resistance needed.
Chipper Jones: Injuries really derailed his opportunity, but he certainly had the homeruns and BABIP, his strikeouts were a bit uncharacteristic though.
Derek Jeter: The BABIP has been there on quite a few occasions for Jeter, but the strikeouts and declining homerun rates are almost definitely keeping him out of the .400 club.
Joe Mauer: He's got quite a few years to try it. His BABIP has crept over .360 once all ready, and he won the batting title because of it. Doesn't strike out a ton, but isn't trotting around the bases quite as much as he would need to. Also, I do question his longevity if he remains a catcher.
Alex Rodriguez: If this post were written following 1996 I would've likely said he'll be there by now. Strikes out too much to realistically have a shot moving forward, but man, his 1996 had the perfect storm going.