Granted the average GPA's shown on these tables are around 3.2 for Active Duty, however that is an average GPA and does not take into account the other tangibles such as LDAC, PT, Leadership, and PMS scores, all of which go into calculating your OMS. If the average is 3.2 and considering the top GPA is probably 4.0 then the lowest GPA will be much lower then 3.2.
An example of this can be found in my own son's score. He went into the OML with a 3.5 GPA, he was 6.45% on the national OML and 10.45% on the AD OML. A classmate of his ended with a 3.8, he placed 21% on the national OML and 36% on the AD OML. Just keep in mind that GPA, while important, is not the only contributing factor in the OML.