Japanese pitchers traditionally have a difficult learning curve when they come to pitch in MLB. The biggest reasons for this is the size of the baseball and the days in between starts. The baseball used in the Pacific and Central Leagues of Japan is slightly smaller. Gripping and controlling the Major League ball is something to get used to and doesn’t always translate to immediate success.
More than the size of the ball is the length of time in between starts. In Japan, a pitcher usually pitches once a week with six days rest in between starts. In MLB, a pitcher usually pitches every five days. Those two extra days of rest can really make a difference.
Kawakami had a rough April for Atlanta, but seemed to figure things out in his fifth start of the season. This could be chalked up to getting used to the new baseball. But lets look closer at his rest in between starts. When Kawakami starts on four days rest, he is 2-5 with a 4.26 ERA, 1.54 WHIP, averaging 5.3 innings and 3.54 strikeouts per outing. When he pitches with five days rest, he is 2-3 with a 3.95 ERA, 1.06 WHIP, averaging 6.3 IP and 4.29 Ks per start. These stats show a dramatic difference when Kawakami gets that one extra day in between starts. Kawakami’s next start comes on Saturday, giving him six days rest which he has not done this season, but similar to the conditions that he thrived under in Japan. It will be interesting to see how he performs, but I’d wager he’ll be better than his usual MLB self in that start.