Hiroki Kuroda is a statistical anomaly.
The 38-year-old is pitching to the lowest ERA of his career in a hitter-friendly home park in a hitter-friendly league.
Before coming to the United States, Kuroda pitched 10 seasons for the Hiroshima Carp, posting a 3.77 ERA with 6.62 strikeouts per nine innings and 2.38 walks per nine innings from 1997-2007 in Japan's Central League.
It's difficult to equate baseball in Japan with Major League Baseball but most analysts agree that the level of difficulty is somewhere in between Triple-A and the majors, the proverbial Quadruple-A.
Given that Kuroda pitched his prime-age seasons -- 22-32 years old -- in an environment that is typically seen as easier than MLB, you would expect his performance to trend downward upon arriving in the United States.
And Kuroda would prove you wrong.
Signing with the Dodgers before the 2008 season, Kuroda pitched four seasons in Los Angeles and thrived. He had a 3.73 ERA during his first season at Chavez Ravine and shaved that down to 3.07 by 2011. In four seasons, he compiled a 3.45 ERA.
That's when he was lured to New York, where he has pitched for the Yankees the past two seasons. Getting fitted for pinstripes has generally not been kind to former National League pitchers. Since the failures of the likes of Kevin Brown, Javier Vazquez, Carl Pavano, Jaret Wright and Randy Johnson, general manager Brian Cashman has generally stayed away from acquiring starters who have built a good portion of their reputation in the NL.
The difference in the leagues is plain enough to see -- AL starters have a 4.23 ERA this season and NL starters have a 3.95 ERA, not having to face a designated hitter most nights.
But Kuroda, again, bucked the trend.
After giving up two runs in eight innings against Oakland on Thursday, Kuroda has lowered his 2013 ERA to 2.78, 20th among all qualified starters in MLB and eighth in the American League.
In his two AL seasons, Kuroda has a 3.17 ERA, his lowest in any league.
During the past six seasons combined, Kuroda ranks 21st among qualified starters in wins above replacement, an advanced stat that measures a player's total contributions to his team. His 17.2 WAR ranks him just behind Josh Beckett and Ryan Dempster and ahead of pitchers such as Jake Peavy and Anibal Sanchez.
As the competition gets tougher, it seems Kuroda does, too. But statistically, not much of what he's done has changed as he's aged and excelled.
Kuroda had a 6.6 K/9 rate in Japan, 6.7 rate in the NL and has a 6.7 rate in the AL. His 2.3 BB/9 rate in Japan fell slightly to 2.1 in the NL and 2.1 in the AL. His home runs per nine innings hasn't changed in any league: 0.9.
Proving that even in an anomaly, there can be consistency.