How is this possible to have an OBP lower than your BA?

[brewcrewfan08]

I was looking at Ryan Braun's stats for the year because i wanted to know how he started off the first 10 games or so, but then i saw that his OBP in May was lower than his BA, how is this possible?

 

Here is the link to his stat page

 

http://mlb.mlb.com/stats/individual_player_gamebygamelog.jsp?playerID=460075&statType=1

 

 

EDIT: Please use more descriptive subject lines - Brian

[trwi7]

It has to do with sacrifice flies.

On base percentage is calculated by Hits+walks+hit by pitches divided by at bats+walks+hit by pitches+sacrifice flies.

In Braun's case he was 6-27 (.222 batting average) but he didn't have any walks or hit by pitches but he did have 1 sacrifice fly so instead of keeping it 6-27 you divide 6 by 28 for a .214 OBP.