In our first post, we showed the percentage of players in Major League Baseball based on birth month. As I showed, there is a much higher percentage of players born in August, largely due to the Little League Baseball cutoff date of July 31.
In order for players to reach the majors, they had to have been performing at a higher level through various levels of baseball. But once they reach the major league level, is there any correlation between birth month and performance? Let’s take a look.
Batting
Interestingly, the statistics show that, if anything, players born in JULY outperform those born in August. While 2 HR and 5RBI isn’t huge, it still interesting to see that players born in July outperform those born in August.
Pitching
There is very little difference in pitching statistics relative to birth month. Players born in August pitched more innings, and had a slightly lower ERA, but no extreme differences between people born in July and August.
Conclusion
Wile there was a huge difference in the percentage of players born in July (6.4%) compared to August (12.2%), the difference in performance was fairly small. How could this be?
The theory is that by the time a player reaches the Major League, they are an expert, and thus in aggregate the statistics are very similar. Any other thoughts? There are more players born in August, yet their performance isn’t any better. What other explanations can you think of?
While HR, RBI, and AVG are good barometers to consider, I think it would be interesting to look at OBP and OPS as well. Perhaps those figures would shed some more light on the analysis and give you more data to see if there is a reliable trend in offensive statistics based on birth month. Also, why not compare August to every other month, as opposed to just July? Its interesting that there seems to be a very real correlation between birth month with regard to making the bigs, but I would doubt there's any real correlation to birth month and performance once a player makes it.
I agree that OBP and OPS would better illustrate offensive success. I used AB, HR, RBI and only showed July/August to make it easier to understand for the casual fan (or blog reader). Given the interest in the topic, I'll likely post a Part III that goes into greater depth with OBP, OPS and detailed breakdown by month.