Unless my memory of statistics is failing me, multiple sets with the same medians are going to end up approximating the median as a whole - i.e., I think 3.3 should be somewhere around the 1L-wide median.
The mean, on the other hand, is significantly greater than the median (I think) because the grade distribution is skewed. Basically I think if you graphed out 1L grades they'd look like a chi square distribution. But there's a reason no one cares about the mean.
As far as whether median is competitive for OCI, that's a question for the 2Ls. My impression is that if you're biglaw or bust you would do well to raise it at least a bit 2nd semester but from what I've heard it seems that, at least at peer schools, median will not kill you as long as you're smart about your bidding strategy. When I came for ASO last March I met a now 3L who said she definitely wasn't top third and got a biglaw offer in DC. Take from that what you will.